Clear to circular polarizing photochromic devices and methods of making the same

ABSTRACT

The present invention provides optical elements comprising a photochromic linear polarizing element and a birefringent layer that circularly or elliptically polarizes transmitted radiation. The photochromic linear polarizing element comprises a substrate and either: (1) a coating comprising an aligned, thermally reversible photochromic-dichroic compound having an average absorption ratio of at least 1.5 in an activated state, and being operable for switching from a first absorption state to a second absorption state in response to actinic radiation, to revert back to the first absorption state in response to thermal energy, and to linearly polarize transmitted radiation in at least one of the two states; or (2) an at least partially ordered polymeric sheet connected to the substrate; and a thermally reversible photochromic-dichroic compound that is at least partially aligned with the polymeric sheet and has an average absorption ratio greater than 2.3 in the activated state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/590,055, filed Oct. 31, 2006, which is a divisional of U.S.Pat. No. 7,256,921, which in turn claims the benefit of U.S. ProvisionalApplication Ser. No. 60/484,100, filed Jul. 1, 2003, each of which ishereby specifically incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A SEQUENCE LISTING

Not applicable.

BACKGROUND OF THE INVENTION

Various embodiments disclosed herein relate generally to opticalelements, security liquid crystal cells and methods of making the same.

Display screens on mobile devices, ATM's, and other machines that may beused outdoors often have problems with sunlight readability, UVdegradation, durability, operating temperature range, and lifetime.Sunlight readability may be improved in a number of ways. One solutionis to actively increase the backlight intensity by adding morecold-cathode-fluorescent-lamp (CCFL) backlight tubes. Unfortunately,this approach has drawbacks in most mobile device applications becauseof battery drain, larger device size, heat generation, and weightconsiderations. A second approach is to passively increase backlightintensity by adding brightness-enhancement films to the optical stack ofthe LCD. While avoiding most of the drawbacks of the active approach,this solution only increases brightness by a factor of about two, whichis insufficient to solve the sunlight readability problem. A thirdsolution is the minimization of reflected light, such as through the useof anti-reflective coatings and films and circular polarizers. Each ofthese solutions may be combined with others to optimize the desiredeffect.

A circular polarizer is an assembly of a conventional linearlypolarizing element and a quarter wave retarder. The axis of the retarderis oriented at 45 degrees with respect to the axis of the linearpolarizer. As incident light passes through the assembly, it isconverted to circularly polarized light. Circular polarizers havetraditionally been used for their antireflective properties. In suchapplications, when light is reflected back from a specular surfacethrough the retarder, the plane of polarization is rotated 90 degreeswith respect to the original orientation so the linear polarizer blocksthe returning reflected light.

Conventional linearly polarizing elements, such as linearly polarizinglenses for sunglasses and linearly polarizing filters, are typicallyformed from stretched polymer sheets containing a dichroic material,such as a dichroic dye. The conventional linearly polarizing elementsare static elements having a single, linearly polarizing state. Thuswhen a conventional linearly polarizing element is exposed to eitherrandomly polarized radiation or reflected radiation of the appropriatewavelength, some percentage of the radiation transmitted through theelement will be linearly polarized. As used herein the term “linearlypolarize” means to confine the vibrations of the electric vector oflight waves to one direction or plane.

Further, conventional linearly polarizing elements are typically tintedusing a coloring agent (i.e., the dichroic material) and have anabsorption spectrum that does not vary in response to actinic radiation.As used herein “actinic radiation” means electromagnetic radiation, suchas but not limited to ultraviolet and visible radiation that is capableof causing a response. The color of the conventional linearly polarizingelement will depend upon the coloring agent used to form the element,and most commonly is a neutral color (for example, brown or gray). Whileconventional linearly polarizing elements are useful in reducingreflected light glare, because of their tint they are not well suitedfor use under certain low-light conditions. Further, becauseconventional linearly polarizing elements have only a single, tintedlinearly polarizing state, they are limited in their ability to store ordisplay information.

As discussed above, conventional linearly polarizing elements aretypically formed using sheets of stretched polymer films containing adichroic material. As used herein the term “dichroic” means capable ofabsorbing one of two orthogonal plane polarized components oftransmitted radiation more strongly than the other. Thus, while dichroicmaterials are capable of preferentially absorbing one of two orthogonalplane polarized components of transmitted radiation, if the molecules ofthe dichroic material are not suitably positioned or arranged, no netlinear polarization of transmitted radiation will be achieved. That is,due to the random positioning of the molecules of the dichroic material,selective absorption by the individual molecules will cancel each othersuch that no net or overall linear polarizing effect is achieved. Thus,it is generally necessary to suitably position or arrange the moleculesof the dichroic material by alignment with another material in order toachieve a net linear polarization.

One common method of aligning the molecules of a dichroic dye involvesheating a sheet or layer of polyvinyl alcohol (“PVA”) to soften the PVAand then stretching the sheet to orient the PVA polymer chains. Then thedichroic dye is impregnated into the stretched sheet and dye moleculestake on the orientation of the polymer chains. That is, the dyemolecules become aligned such that the long axis of the dye molecule aregenerally parallel to the oriented polymer chains. Alternatively, thedichroic dye can be first impregnated into the PVA sheet, and then thesheet can be heated and stretched as described above to orient the PVApolymer chains and associated dye. This allows the molecules of thedichroic dye to be suitably positioned or arranged within the orientedpolymer chains of the PVA sheet and a net linear polarization to beachieved. That is, the PVA sheet can be made to linearly polarizetransmitted radiation, or in other words, a linearly polarizing filtercan be formed.

In contrast to the dichroic elements discussed above, conventionalphotochromic elements, such as photochromic lenses that are formed usingconventional thermally reversible photochromic materials are generallycapable of converting from a first state, for example a “clear state,”to a second state, for example a “colored state,” in response to actinicradiation, and reverting back to the first state in response to thermalenergy. As used herein the term “photochromic” means having anabsorption spectrum for at least visible radiation that varies inresponse to at least actinic radiation. Thus, conventional photochromicelements are generally well suited for use in both low-light and brightconditions. However, conventional photochromic elements that do notinclude linearly polarizing filters are generally not adapted tolinearly polarize radiation. That is, the absorption ratio ofconventional photochromic elements, in either state, is generally lessthan two. As used herein the term “absorption ratio” refers to the ratioof the absorbance of radiation linearly polarized in a first plane tothe absorbance of the same wavelength radiation linearly polarized in aplane orthogonal to the first plane, wherein the first plane is taken asthe plane with the highest absorbance. Therefore, conventionalphotochromic elements cannot reduce reflected light glare to the sameextent as conventional linearly polarizing elements. Further,conventional photochromic elements have a limited ability to store ordisplay information.

Accordingly, it would be advantageous to provide elements and devicesthat are adapted to display both linearly polarizing and photochromicproperties. Further, it would be advantageous to provide elements anddevices that are adapted to display circular or elliptical polarizationand photochromic properties, for example, in an effort to improvesunlight readability of display screens. Such elements and devices canalso be used to improve visibility through packaging materials andprotect light-sensitive items contained within the packaging materials.

SUMMARY OF THE DISCLOSURE

The present invention provides an optical element comprising:

(a) a photochromic linear polarizing element comprising:

(i) a substrate; and

(ii) a coating connected to the substrate, the coating having a firstabsorption state and a second absorption state and being operable forswitching from the first absorption state to the second absorption statein response to actinic radiation, to revert back to the first absorptionstate in response to actinic radiation and/or thermal energy, and tolinearly polarize transmitted radiation in the first absorption stateand/or the second absorption state; wherein the coating (ii) comprisesan at least partially aligned, thermally reversiblephotochromic-dichroic material having an average absorption ratio of atleast 1.5 in an activated state; and

(b) a birefringent layer connected to the photochromic linear polarizingelement (a), the birefringent layer being operable to circularly orelliptically polarize transmitted radiation. Note that the coating neednot cover the entire surface of the substrate; i.e., it may be a partialcoating.

In a separate embodiment, the present invention provides a compositeoptical element comprising:

(a) a photochromic linear polarizing element comprising:

(i) an at least partially ordered polymeric sheet; and

(ii) a reversible photochromic-dichroic material that is at leastpartially aligned with the polymeric sheet and has an average absorptionratio of at least 1.5 in the activated state; and

(b) a birefringent layer connected to the photochromic linear polarizingelement (a), the birefringent layer being operable to circularly orelliptically polarize transmitted radiation.

BRIEF DESCRIPTION OF THE VIEW OF THE DRAWING

Various embodiments of the present invention will be better understoodwhen read in conjunction with the drawing, in which:

FIG. 1 shows two average difference absorption spectra obtained for acoating according to various embodiment disclosed herein.

FIG. 2 is a schematic, cross-sectional view of an overmolding assemblyaccording to one non-limiting embodiment disclosed herein.

DETAILED DESCRIPTION OF EMBODIMENTS

As used in this specification and the appended claims, the articles “a,”“an,” and “the” include plural referents unless expressly andunequivocally limited to one referent.

Additionally, for the purposes of this specification, unless otherwiseindicated, all numbers expressing quantities of ingredients, reactionconditions, and other properties or parameters used in the specificationare to be understood as being modified in all instances by the term“about.” Accordingly, unless otherwise indicated, it should beunderstood that the numerical parameters set forth in the followingspecification and attached claims are approximations. At the very least,and not as an attempt to limit the application of the doctrine ofequivalents to the scope of the claims, numerical parameters should beread in light of the number of reported significant digits and theapplication of ordinary rounding techniques.

Further, while the numerical ranges and parameters setting forth thebroad scope of the invention are approximations as discussed above, thenumerical values set forth in the Examples section are reported asprecisely as possible. It should be understood, however, that suchnumerical values inherently contain certain errors resulting from themeasurement equipment and/or measurement technique.

Optical elements and devices according to various embodiments of thepresent invention will now be described. Various embodiments disclosedherein provide an optical element comprising a substrate and a coatinghaving a first state and a second state connected to the substrate, thecoating being operable to switch from the first state to the secondstate in response to actinic (and/or other) radiation, to revert back tothe first state in response to thermal energy, and to linearly polarizetransmitted radiation in at least one of the first state and the secondstate. As used herein, the term “thermal energy” means any form of heat.

As used herein to modify the term “state,” the terms “first” and“second” are not intended to refer to any particular order orchronology, but instead refer to two different conditions or properties.For example, although not limiting herein, the first state and thesecond state of the coating may differ with respect to at least oneoptical property, such as but not limited to the absorption or linearlypolarization of visible and/or UV radiation. Thus, according to variousembodiments disclosed herein, the coating can be adapted to have adifferent absorption spectrum in each of the first and second state. Forexample, while not limiting herein, the coating can be clear in thefirst state and colored in the second state. Alternatively, the coatingcan be adapted to have a first color in the first state and a secondcolor in the second state. Further, as discussed below in more detail,the coating can be adapted to not be linearly polarizing (or“non-polarizing”) in the first state and linearly polarizing in thesecond state.

As used herein the term “optical” means pertaining to or associated withlight and/or vision. For example, according to various embodimentsdisclosed herein, the optical element or device can be chosen fromophthalmic elements and devices, display elements and devices, windows,mirrors, packaging materials such as clear packaging materials includingshrink wrap and clear removable protective overlays and packagingmaterials prepared from polymeric materials such as any of the polymericsubstrates described herein below, and active and passive liquid crystalcell elements and devices. As used herein the term “ophthalmic” meanspertaining to or associated with the eye and vision. Examples ofophthalmic elements include corrective and non-corrective lenses,including single vision or multi-vision lenses, which may be eithersegmented or non-segmented multi-vision lenses (such as, but not limitedto, bifocal lenses, trifocal lenses and progressive lenses), as well asother elements used to correct, protect, or enhance (cosmetically orotherwise) vision, including without limitation, contact lenses,intra-ocular lenses, magnifying lenses, and protective lenses or visors.As used herein the term “display” means the visible or machine-readablerepresentation of information in words, numbers, symbols, designs ordrawings. Examples of display elements and devices include screens,monitors, and security elements, such as security marks. As used hereinthe term “window” means an aperture adapted to permit the transmissionof radiation therethrough. Examples of windows include automotive andaircraft transparencies, filters, shutters, and optical switches. Asused herein the term “mirror” means a surface that specularly reflects alarge fraction of incident light.

As used herein, the term “light-sensitive” products includes foodstuffs,cosmetics, pharmaceuticals, optical devices, electronic components, etc.that upon exposure to light demonstrate an adverse effect such asspoilage, premature aging, inactivation of active or functionalcomponents, as known to those skilled in the art.

As used herein the term “liquid crystal cell” refers to a structurecontaining a liquid crystal material that is capable of being ordered.Active liquid crystal cells are cells wherein the liquid crystalmaterial is capable of being switched between ordered and disorderedstates or between two ordered states by the application of an externalforce, such as electric or magnetic fields. Passive liquid crystal cellsare cells wherein the liquid crystal material maintains an orderedstate. One example of an active liquid crystal cell element or device isa liquid crystal display.

As used herein the term “coating” means a supported film derived from aflowable composition, which may or may not have a uniform thickness, andspecifically excludes polymeric sheets. As used herein the term “sheet”means a pre-formed film having a generally uniform thickness and capableof self-support. Further, as used herein the term “connected to” meansin direct contact with an object or indirect contact with an objectthrough one or more other structures or materials, at least one of whichis in direct contact with the object. Thus, according to variousembodiments disclosed herein, the coating having the first state and thesecond state can be in direct contact with at least a portion of thesubstrate or it can be in indirect contact with at least a portion ofthe substrate through one or more other structures or materials. Forexample, although not limiting herein, the coating can be in contactwith one or more other at least partial coatings, polymer sheets orcombinations thereof, at least one of which is in direct contact with atleast a portion of the substrate.

Generally speaking, substrates that are suitable for use in conjunctionwith various embodiments disclosed herein include, but are not limitedto, substrates formed from organic materials, inorganic materials, orcombinations thereof (for example, composite materials). Examples ofsubstrates that can be used in accordance with various embodimentsdisclosed herein are described in more detail below.

Specific examples of organic materials that may be used to form thesubstrates disclosed herein include polymeric materials, for examples,homopolymers and copolymers, prepared from the monomers and mixtures ofmonomers disclosed in U.S. Pat. No. 5,962,617 and in U.S. Pat. No.5,658,501 from column 15, line 28 to column 16, line 17, the disclosuresof which U.S. patents are specifically incorporated herein by reference.For example, such polymeric materials can be thermoplastic or thermosetpolymeric materials, can be transparent or optically clear, and can haveany refractive index required. Examples of such disclosed monomers andpolymers include: polyol(allyl carbonate) monomers, e.g., allyl diglycolcarbonates such as diethylene glycol bis(allyl carbonate), which monomeris sold under the trademark CR-39 by PPG Industries, Inc.;polyurea-polyurethane (polyurea-urethane) polymers, which are prepared,for example, by the reaction of a polyurethane prepolymer and a diaminecuring agent, a composition for one such polymer being sold under thetrademark TRIVEX by PPG Industries, Inc.; polyol(meth)acryloylterminated carbonate monomer; diethylene glycol dimethacrylate monomers;ethoxylated phenol methacrylate monomers; diisopropenyl benzenemonomers; ethoxylated trimethylol propane triacrylate monomers; ethyleneglycol bismethacrylate monomers; poly(ethylene glycol) bismethacrylatemonomers; urethane acrylate monomers; poly(ethoxylated bisphenol Adimethacrylate); poly(vinyl acetate); poly(vinyl alcohol); poly(vinylchloride); poly(vinylidene chloride); polyethylene; polypropylene;polyurethanes; polythiourethanes; thermoplastic polycarbonates, such asthe carbonate-linked resin derived from bisphenol A and phosgene, onesuch material being sold under the trademark LEXAN; polyesters, such asthe material sold under the trademark MYLAR; poly(ethyleneterephthalate); polyvinyl butyral; poly(methyl methacrylate), such asthe material sold under the trademark PLEXIGLAS, and polymers preparedby reacting polyfunctional isocyanates with polythiols or polyepisulfidemonomers, either homopolymerized or co- and/or terpolymerized withpolythiols, polyisocyanates, polyisothiocyanates and optionallyethylenically unsaturated monomers or halogenated aromatic-containingvinyl monomers. Also contemplated are copolymers of such monomers andblends of the described polymers and copolymers with other polymers, forexample, to form block copolymers or interpenetrating network products.

While not limiting herein, according to various embodiments disclosedherein, the substrate can be an ophthalmic substrate. As used herein theterm “ophthalmic substrate” means lenses, partially formed lenses, andlens blanks. Examples of organic materials suitable for use in formingophthalmic substrates according to various embodiments disclosed hereininclude, but are not limited to, the art-recognized polymers that areuseful as ophthalmic substrates, e.g., organic optical resins that areused to prepare optically clear castings for optical applications, suchas ophthalmic lenses.

Other examples of organic materials suitable for use in forming thesubstrates according to various embodiments disclosed herein includeboth synthetic and natural organic materials, including withoutlimitation: opaque or translucent polymeric materials, natural andsynthetic textiles, and cellulosic materials such as, paper and wood.

Examples of inorganic materials suitable for use in forming thesubstrates according to various embodiments disclosed herein includeglasses, minerals, ceramics, and metals. For example, in one embodimentthe substrate can comprise glass. In other embodiments, the substratecan have a reflective surface, for example, a polished ceramicsubstrate, metal substrate, or mineral substrate. In other embodiments,a reflective coating or layer can be deposited or otherwise applied to asurface of an inorganic or an organic substrate to make it reflective orto enhance its reflectivity.

Further, according to certain embodiments disclosed herein, thesubstrates may have a protective coating, such as, but not limited to,an abrasion-resistant coating, such as a “hard coat,” on their exteriorsurfaces. For example, commercially available thermoplasticpolycarbonate ophthalmic lens substrates are often sold with anabrasion-resistant coating already applied to its exterior surfacesbecause these surfaces tend to be readily scratched, abraded or scuffed.An example of such a lens substrate is the GENTEX™ polycarbonate lens(available from Gentex Optics). Therefore, as used herein the term“substrate” includes a substrate having a protective coating, such asbut not limited to an abrasion-resistant coating, on its surface(s).

Still further, the substrates according to various embodiments disclosedherein can be untinted, tinted, linearly polarizing, circularlypolarizing, elliptically polarizing, photochromic, ortinted-photochromic substrates. As used herein with reference tosubstrates the term “untinted” means substrates that are essentiallyfree of coloring agent additions (such as, but not limited to,conventional dyes) and have an absorption spectrum for visible radiationthat does not vary significantly in response to actinic radiation.Further, with reference to substrates the term “tinted” means substratesthat have a coloring agent addition (such as, but not limited to,conventional dyes) and an absorption spectrum for visible radiation thatdoes not vary significantly in response to actinic radiation.

As used herein the term “linearly polarizing” with reference tosubstrates refers to substrates that are adapted to linearly polarizeradiation. As used herein the term “circularly polarizing” withreference to substrates refers to substrates that are adapted tocircularly polarize radiation. As used herein the term “ellipticallypolarizing” with reference to substrates refers to substrates that areadapted to elliptically polarize radiation. As used herein with the term“photochromic” with reference to substrates refers to substrates havingan absorption spectrum for visible radiation that varies in response toat least actinic radiation. Further, as used herein with reference tosubstrates, the term “tinted-photochromic” means substrates containing acoloring agent addition as well as a photochromic material, and havingan absorption spectrum for visible radiation that varies in response toat least actinic radiation. Thus, for example and without limitation,the tinted-photochromic substrate can have a first color characteristicof the coloring agent and a second color characteristic of thecombination of the coloring agent the photochromic material when exposedto actinic radiation.

As previously discussed, conventional linearly polarizing elements aretypically formed using stretched polymer sheets and a dichroic dye.However, these conventional linearly polarizing elements generally havea single tinted, linearly polarizing state. As previously discussed, theterm “linearly polarize” means to confine the vibrations of the electricvector of light waves to one direction. Further, as previouslydiscussed, conventional photochromic elements are formed fromconventional photochromic compounds and have at least two states, forexample a clear state and a colored state. As previously discussed, theterm “photochromic” means having an absorption spectrum for at leastvisible radiation that varies in response to at least actinic radiation.However, conventional photochromic elements are generally not adapted tolinearly polarize radiation.

As discussed above, the optical elements according to variousembodiments disclosed herein comprise a coating (ii) connected to thesubstrate, the coating having a first absorption state and a secondabsorption state, typically switching from the first state to the secondstate in response to actinic radiation, reverting back to the firststate in response to actinic and/or thermal energy, and demonstratinglinear polarization in at least one of the first state and the secondstate. That is, the optical elements according to various embodimentsdisclosed herein can be photochromic-dichroic elements. As used hereinthe term “photochromic-dichroic” means displaying both photochromic anddichroic (i.e., linearly polarizing) properties under certainconditions, which properties are at least detectible by instrumentation.Further, as discussed below in more detail, the optical elementsaccording to various embodiments disclosed herein can be formed using atleast one photochromic-dichroic compound that is at least partiallyaligned.

As previously mentioned, according to various embodiments disclosedherein, the coating can be non-polarizing in the first state (that is,the coating will not confine the vibrations of the electric vector oflight waves to one direction) and linearly polarizing transmittedradiation in the second state. As used herein the term “transmittedradiation” refers to radiation that is passed through at least a portionof an object. Although not limiting herein, the transmitted radiationcan be ultraviolet radiation, visible radiation, or a combinationthereof. Thus, according to various embodiments disclosed herein, thecoating can be non-polarizing in the first state and linearly polarizingtransmitted ultraviolet radiation, transmitted visible radiation, or acombination thereof in the second state.

According to still other embodiments, the coating (ii) can have a firstabsorption spectrum in the first state, a second absorption spectrum inthe second state, and to be linearly polarizing in both the first andsecond states.

According to certain embodiments, the coating (ii) can have an averageabsorption ratio of at least 1.5 in at least one state. For example, thecoating can have an average absorption ratio ranging from at least 1.5to 50 (or greater) in at least one state. As previously discussed, theterm “absorption ratio” refers to the ratio of the absorbance ofradiation linearly polarized in a first plane to the absorbance ofradiation linearly polarized in a plane orthogonal to the first plane,wherein the first plane is taken as the plane with the highestabsorbance. Thus, the absorption ratio (and the average absorption ratiowhich is described below) is an indication of how strongly one of twoorthogonal plane polarized components of radiation is absorbed by anobject or material.

The average absorption ratio of a coating or element comprising aphotochromic-dichroic compound can be determined as set forth below. Forexample, to determine the average absorption ratio of a coatingcomprising a photochromic-dichroic compound, a substrate having acoating is positioned on an optical bench and the coating is placed in alinearly polarizing state by activation of the photochromic-dichroiccompound. Activation is achieved by exposing the coating to UV radiationfor a time sufficient to reach a saturated or near saturated state (thatis, a state wherein the absorption properties of the coating do notsubstantially change over the interval of time during which themeasurements are made). Absorption measurements are taken over a periodof time (typically 10 to 300 seconds) at 3 second intervals for lightthat is linearly polarized in a plane perpendicular to the optical bench(referred to as the 0° polarization plane or direction) and light thatis linearly polarized in a plane that is parallel to the optical bench(referred to as the 900 polarization plane or direction) in thefollowing sequence: 0°, 90°, 90°, 0° etc. The absorbance of the linearlypolarized light by the coating is measured at each time interval for allof the wavelengths tested and the unactivated absorbance (i.e., theabsorbance of the coating in an unactivated state) over the same rangeof wavelengths is subtracted to obtain absorption spectra for thecoating in an activated state in each of the 0° and 90° polarizationplanes to obtain an average difference absorption spectrum in eachpolarization plane for the coating in the saturated or near-saturatedstate.

For example, with reference to FIG. 1, there is shown the averagedifference absorption spectrum (generally indicated 10) in onepolarization plane that was obtained for a coating according to oneembodiment disclosed herein. The average absorption spectrum (generallyindicated 11) is the average difference absorption spectrum obtained forthe same coating in the orthogonal polarization plane.

Based on the average difference absorption spectra obtained for thecoating, the average absorption ratio for the coating is obtained asfollows. The absorption ratio of the coating at each wavelength in apredetermined range of wavelengths corresponding to λ_(max-vis)+/−5nanometers (generally indicated as 14 in FIG. 1), wherein λ_(max-vis) isthe wavelength at which the coating had the highest average absorbancein any plane, is calculated according to the following equation:

AR _(λi) =Ab ¹ _(λi) /Ab ² _(λi)  Eq. 1

wherein, AR_(λi) is the absorption ratio at wavelength λ_(i), Ab¹ _(λi)is the average absorption at wavelength λ_(i) in the polarizationdirection (i.e., 0° or 90°) having the higher absorbance, and Ab² _(λi)is the average absorption at wavelength λ_(i) in the remainingpolarization direction. As previously discussed, the “absorption ratio”refers to the ratio of the absorbance of radiation linearly polarized ina first plane to the absorbance of the same wavelength radiationlinearly polarized in a plane orthogonal to the first plane, wherein thefirst plane is taken as the plane with the highest absorbance.

The average absorption ratio (“AR”) for the coating is then calculatedby averaging the individual absorption ratios over the predeterminedrange of wavelengths (i.e., λ_(max-vis)+/−5 nanometers) according to thefollowing equation:

AR=(ΣAR _(λi))/n _(i)  Eq. 2

wherein, AR is average absorption ratio for the coating, AR_(λi) are theindividual absorption ratios (as determined above in Eq. 1) for eachwavelength within the predetermined range of wavelengths, and n_(i) isthe number of individual absorption ratios averaged. A more detaileddescription of this method of determining the average absorption ratiois provided in the Examples.

As previously mentioned, according to various embodiments disclosedherein, the coating (ii) can comprise at least one photochromic-dichroicmaterial that is at least partially aligned. As previously discussed,the term “photochromic-dichroic” means displaying both photochromic anddichroic (i.e., linearly polarizing) properties under certainconditions, which properties are at least detectible by instrumentation.Accordingly, “photochromic-dichroic materials” are compounds displayingboth photochromic and dichroic (i.e., linearly polarizing) propertiesunder certain conditions, which properties are at least detectible byinstrumentation. Thus, photochromic-dichroic compounds have anabsorption spectrum for at least visible radiation that varies inresponse to at least actinic radiation and are capable of absorbing oneof two orthogonal plane polarized components of at least transmittedradiation more strongly than the other. Additionally, as withconventional photochromic compounds discussed above, thephotochromic-dichroic compounds disclosed herein can be thermallyreversible. That is, the photochromic-dichroic compounds can switch froma first state to a second state in response to actinic radiation andrevert back to the first state in response to thermal energy. As usedherein the term “compound” means a substance formed by the union of twoor more elements, components, ingredients, or parts and includes,without limitation, molecules and macromolecules (for example polymersand oligomers) formed by the union of two or more elements, components,ingredients, or parts.

For example, according to various embodiments disclosed herein, thephotochromic-dichroic compound can have a first state having a firstabsorption spectrum, a second state having a second absorption spectrumthat is different from the first absorption spectrum, and can be adaptedto switch from the first state to the second state in response to atleast actinic radiation and to revert back to the first state inresponse to thermal energy. Further, the photochromic-dichroic compoundcan be dichroic (i.e., linearly polarizing) in one or both of the firststate and the second state. For example, although not required, thephotochromic-dichroic compound can be linearly polarizing in anactivated state and non-polarizing in the bleached or faded (i.e., notactivated) state. As used herein, the term “activated state” refers tothe photochromic-dichroic compound when exposed to sufficient actinicradiation to cause the at least a portion of the photochromic-dichroiccompound to switch from a first state to a second state. Further,although not required, the photochromic-dichroic compound can bedichroic in both the first and second states. While not limiting herein,for example, the photochromic-dichroic compound can linearly polarizevisible radiation in both the activated state and the bleached state.Further, the photochromic-dichroic compound can linearly polarizevisible radiation in an activated state, and can linearly polarize UVradiation in the bleached state.

Although not required, according to various embodiments disclosedherein, the photochromic-dichroic compound can have an averageabsorption ratio of at least 1.5 in an activated state as determinedaccording to the CELL METHOD. For example, the photochromic-dichroiccompound can have an average absorption ratio greater than 2.3 in anactivated state as determined according to the CELL METHOD. According tostill other embodiments, the photochromic-dichroic compound can have anaverage absorption ratio ranging from 1.5 to 50 in an activated state asdetermined according to the CELL METHOD. According to other embodiments,the photochromic-dichroic compound can have an average absorption ratioranging from 4 to 20, or from 3 to 30, or from 2.5 to 50 in an activatedstate as determined according to the CELL METHOD. However, generallyspeaking, the average absorption ratio of the photochromic-dichroiccompound can be any average absorption ratio that is sufficient toimpart the desired properties to the device or element. Examples ofsuitable photochromic-dichroic compounds are described in detail hereinbelow.

The CELL METHOD for determining the average absorption ratio of thephotochromic-dichroic compound is essentially the same as the methodused to determine the average absorption ratio of the coating (describedabove and in the Examples), except that, instead of measuring theabsorbance of a coated substrate, a cell assembly containing an alignedliquid crystal material and the photochromic-dichroic compound istested. More specifically, the cell assembly comprises two opposingglass substrates that are spaced apart by 20 microns+/−1 micron. Thesubstrates are sealed along two opposite edges to form a cell. The innersurface of each of the glass substrates is coated with a polyimidecoating, the surface of which has been at least partially ordered byrubbing. Alignment of the photochromic-dichroic compound is achieved byintroducing the photochromic-dichroic compound and the liquid crystalmedium into the cell assembly, and allowing the liquid crystal medium toalign with the rubbed polyimide surface. Once the liquid crystal mediumand the photochromic-dichroic compound are aligned, the cell assembly isplaced on an optical bench (which is described in detail in theExamples) and the average absorption ratio is determined in the mannerpreviously described for the coated substrates, except that theunactivated absorbance of the cell assembly is subtracted from theactivated absorbance to obtain the average difference absorptionspectra.

As previously discussed, while dichroic compounds are capable ofpreferentially absorbing one of two orthogonal components of planepolarized light, it is generally necessary to suitably position orarrange the molecules of a dichroic compound in order to achieve a netlinear polarization effect. Similarly, it is generally necessary tosuitably position or arrange the molecules of a photochromic-dichroiccompound to achieve a net linear polarization effect. That is, it isgenerally necessary to align the molecules of the photochromic-dichroiccompound such that the long axes of the molecules of thephotochromic-dichroic compound in an activated state are generallyparallel to each other. Therefore, as discussed above, according tovarious embodiments disclosed herein, the photochromic-dichroic compoundis at least partially aligned. Further, if the activated state of thephotochromic-dichroic compound corresponds to a dichroic state of thematerial, the photochromic-dichroic compound can be at least partiallyaligned such that the long axis of the molecules of thephotochromic-dichroic compound in the activated state are aligned. Asused herein the term “align” means to bring into suitable arrangement orposition by interaction with another material, compound or structure.

Further, although not limiting herein, the coating (ii) can comprise aplurality of photochromic-dichroic materials. Although not limitingherein, when two or more photochromic-dichroic compounds are used incombination, the photochromic-dichroic compounds can be chosen tocomplement one another to produce a desired color or hue. For example,mixtures photochromic-dichroic compounds can be used according tocertain embodiments disclosed herein to attain certain activated colors,such as a near neutral gray or near neutral brown. See, for example,U.S. Pat. No. 5,645,767, column 12, line 66 to column 13, line 19, thedisclosure of which is specifically incorporated by reference herein,which describes the parameters that define neutral gray and browncolors. Additionally or alternatively, the coating can comprise mixturesof photochromic-dichroic compounds having complementary linearpolarization states. For example, the photochromic-dichroic compoundscan be chosen to have complementary linear polarization states over adesired range of wavelengths to produce an optical element that iscapable of polarizing light over the desired range of wavelengths. Stillfurther, mixtures of complementary photochromic-dichroic compoundshaving essentially the same polarization states at the same wavelengthscan be chosen to reinforce or enhance the overall linear polarizationachieved. For example, according to one embodiment, the coating havingthe first state and the second state can comprise at least two at leastpartially aligned photochromic-dichroic compounds, wherein thephotochromic-dichroic compounds have complementary colors and/orcomplementary linear polarization states.

As previously discussed, various embodiments disclosed herein provide anoptical element comprising a coating connected to a substrate, whereinthe coating is operable to switch from a first state to a second statein response to actinic radiation, to revert back to the first state inresponse to thermal energy, and to linearly polarize at leasttransmitted radiation in at least one of the first state and the secondstate. Further, according to various embodiments, the coating cancomprise a photochromic-dichroic compound that is at least partiallyaligned.

Additionally, according to various embodiments disclosed herein, thecoating (ii) can further comprise at least one additive that mayfacilitate one or more of the processing, the properties, or theperformance of the coating. Examples of such additives include dyes,alignment promoters, kinetic enhancing additives, photoinitiators,thermal initiators, polymerization inhibitors, solvents, lightstabilizers (such as, but not limited to, ultraviolet light absorbersand light stabilizers, such as hindered amine light stabilizers (HALS)),heat stabilizers, mold release agents, rheology control agents, levelingagents (such as, but not limited to, surfactants), free radicalscavengers, self-assembling materials, gelators, and adhesion promoters(such as hexanediol diacrylate and coupling agents).

Examples of dyes that can be present in the coating according to variousembodiments disclosed herein include organic dyes that are capable ofimparting a desired color or other optical property to the coating.

As used herein, the term “alignment promoter” means an additive that canfacilitate at least one of the rate and uniformity of the alignment of amaterial to which it is added. Examples of alignment promoters that canbe present in the coatings according to various embodiments disclosedherein include those described in U.S. Pat. No. 6,338,808 and U.S.Patent Publication No. 2002/0039627, which are hereby specificallyincorporated by reference herein.

Examples of kinetic enhancing additives that can be present in thecoating according to various embodiments disclosed herein includeepoxy-containing compounds, organic polyols, and/or plasticizers. Morespecific examples of such kinetic enhancing additives are disclosed inU.S. Pat. No. 6,433,043 and U.S. Patent Publication No. 2003/0045612,which are hereby specifically incorporated by reference herein.

Examples of photoinitiators that can be present in the coating accordingto various embodiments disclosed herein include cleavage-typephotoinitiators and abstraction-type photoinitiators. Examples ofcleavage-type photoinitiators include acetophenones,α-aminoalkylphenones, benzoin ethers, benzoyl oximes, acylphosphineoxides and bisacylphosphine oxides or mixtures of such initiators. Acommercial example of such a photoinitiator is DAROCURE® 4265, which isavailable from Ciba Chemicals, Inc. Examples of abstraction-typephotoinitiators include benzophenone, Michler's ketone, thioxanthone,anthraquinone, camphorquinone, fluorone, ketocoumarin or mixtures ofsuch initiators.

Another example of a photoinitiator that can be present in the coatingaccording to various embodiments disclosed herein is a visible lightphotoinitiator. Examples of suitable visible light photoinitiators areset forth at column 12, line 11 to column 13, line 21 of U.S. Pat. No.6,602,603, which is specifically incorporated by reference herein.

Examples of thermal initiators include organic peroxy compounds andazobis(organonitrile) compounds. Specific examples of organic peroxycompounds that are useful as thermal initiators includeperoxymonocarbonate esters, such as tertiarybutylperoxy isopropylcarbonate; peroxydicarbonate esters, such as di(2-ethylhexyl)peroxydicarbonate, di(secondary butyl) peroxydicarbonate anddiisopropylperoxydicarbonate; diacyperoxides, such as2,4-dichlorobenzoyl peroxide, isobutyryl peroxide, decanoyl peroxide,lauroyl peroxide, propionyl peroxide, acetyl peroxide, benzoyl peroxideand p-chlorobenzoyl peroxide; peroxyesters such as t-butylperoxypivalate, t-butylperoxy octylate and t-butylperoxyisobutyrate;methylethylketone peroxide, and acetylcyclohexane sulfonyl peroxide. Inone embodiment the thermal initiators used are those that do notdiscolor the resulting polymerizate. Examples of azobis(organonitrile)compounds that can be used as thermal initiators includeazobis(isobutyronitrile), azobis(2,4-dimethylvaleronitrile) or a mixturethereof.

Examples of polymerization inhibitors include: nitrobenzene,1,3,5,-trinitrobenzene, p-benzoquinone, chloranil, DPPH, FeCl₃, CuCl₂,oxygen, sulfur, aniline, phenol, p-dihydroxybenzene, di-tertiary butylphenol, 1,2,3-trihydroxybenzene, and 2,4,6-trimethylphenol.

Examples of solvents that can be present in the coating according tovarious embodiments disclosed herein include those that will dissolvesolid components of the coating, that are compatible with the coatingand the elements and substrates, and/or can ensure uniform coverage ofthe exterior surface(s) to which the coating is applied. Potentialsolvents include, but are not limited to, the following: propyleneglycol monomethyl ether acetate and their derivates (sold as DOWANOL®industrial solvents), acetone, amyl propionate, anisole, benzene, butylacetate, cyclohexane, dialkyl ethers of ethylene glycol, e.g.,diethylene glycol dimethyl ether and their derivates (sold asCELLOSOLVE® industrial solvents), diethylene glycol dibenzoate, dimethylsulfoxide, dimethyl formamide, dimethoxybenzene, ethyl acetate,isopropyl alcohol, methyl cyclohexanone, cyclopentanone, methyl ethylketone, methyl isobutyl ketone, methyl propionate, propylene carbonate,tetrahydrofuran, toluene, xylene, 2-methoxyethyl ether, 3-propyleneglycol methyl ether, and mixtures thereof.

Examples of self-assembling materials include liquid crystal materialsand/or block copolymers.

Rheology control agents are thickeners that are typically powders thatmay be inorganic, such as silica, organic such as microcrystallinecellulose, hydroxy stearic acid or particulate polymeric materials.Gelators or gelling agents are often organic materials that can alsoaffect the thixotropy of the material in which they are added.Non-limiting examples of suitable gelators or gelling agents include,but are not limited to, natural gums, starches, pectins, agar-agar, andgelatins. Gelators or gelling agents may often be based onpolysaccharides or proteins.

In another embodiment, the coating (ii) can further comprise at leastone conventional dichroic compound. Examples of suitable conventionaldichroic compounds include azomethines, indigoids, thioindigoids,merocyanines, indans, quinophthalonic dyes, perylenes, phthaloperines,triphenodioxazines, indoloquinoxalines, imidazo-triazines, tetrazines,azo and (poly)azo dyes, benzoquinones, naphthoquinones, anthroquinoneand (poly)anthroquinones, anthropyrimidinones, iodine and iodates. Inanother embodiment, the dichroic material can be a polymerizabledichroic compound. That is, the dichroic material can comprise at leastone group that is capable of being polymerized (i.e., a “polymerizablegroup”). For example, although not limiting herein, in one embodimentthe dichroic compound can have at least one alkoxy, polyalkoxy, alkyl,or polyalkyl substituent terminated with at least one polymerizablegroup.

Still further, the coating (ii) can comprise at least one conventionalphotochromic compound. As used herein, the term “conventionalphotochromic compound” includes both thermally reversible andnon-thermally reversible (or photo-reversible) photochromic compounds.Generally, although not limiting herein, when two or more conventionalphotochromic materials are used in combination with each other or with aphotochromic-dichroic compound, the various materials can be chosen tocomplement one another to produce a desired color or hue. For example,mixtures of photochromic compounds can be used according to certainembodiments disclosed herein to attain certain activated colors, such asa near neutral gray or near neutral brown. See, for example, U.S. Pat.No. 5,645,767, column 12, line 66 to column 13, line 19, the disclosureof which is specifically incorporated by reference herein, whichdescribes the parameters that define neutral gray and brown colors.

The optical elements according to various embodiments disclosed hereincan further comprise at least one additional coating that can facilitatebonding, adhering, or wetting of any of the various coatings connectedto the substrate of the optical element. For example, according to oneembodiment, the optical element can comprise an at least partial primercoating between the coating having the first state and the second stateand a portion of the substrate. Further, in some embodiments disclosedherein, the primer coating can serve as a barrier coating to preventinteraction of the coating ingredients with the element or substratesurface and vice versa.

Examples of primer coatings that can be used in conjunction with variousembodiments disclosed herein include coatings comprising couplingagents, at least partial hydrolysates of coupling agents, and mixturesthereof. As used herein “coupling agent” means a material having atleast one group capable of reacting, binding and/or associating with agroup on at least one surface. In one embodiment, a coupling agent canserve as a molecular bridge at the interface of at least two surfacesthat can be similar or dissimilar surfaces. Coupling agents, in anotherembodiment, can be monomers, oligomers, pre-polymers and/or polymers.Such materials include, but are not limited to, organo-metallics such assilanes, titanates, zirconates, aluminates, zirconium aluminates,hydrolysates thereof and mixtures thereof. As used herein the phrase “atleast partial hydrolysates of coupling agents” means that at least someto all of the hydrolyzable groups on the coupling agent are hydrolyzed.In addition to coupling agents and/or hydrolysates of coupling agents,the primer coatings can comprise other adhesion enhancing ingredients.For example, although not limiting herein, the primer coating canfurther comprise an adhesion-enhancing amount of an epoxy-containingmaterial. Adhesion-enhancing amounts of epoxy-containing materials whenadded to the coupling agent containing coating composition can improvethe adhesion of a subsequently applied coating as compared to a couplingagent containing coating composition that is essentially free of theepoxy-containing material. Other examples of primer coatings that aresuitable for use in conjunction with the various embodiments disclosedherein include those described U.S. Pat. No. 6,602,603 and U.S. Pat. No.6,150,430, which are hereby specifically incorporated by reference.

The optical elements according to various embodiments disclosed hereincan further comprise at least one additional coating chosen fromconventional photochromic coatings, anti-reflective coatings, linearlypolarizing coatings, circularly polarizing coatings, ellipticallypolarizing coatings, transitional coatings, primer coatings (such asthose discussed above), and protective coatings such as antifoggingcoatings, oxygen barrier coatings, and ultraviolet light absorbingcoatings connected to at least a portion of the substrate. For example,although not limiting herein, the additional coating(s) can be over atleast a portion of the coating (ii), i.e., as an overcoating; or underat least a portion of the coating (ii), i.e., as an undercoating.Additionally or alternatively, the coating (ii) can be connected to afirst surface of the substrate and the additional coating can beconnected to a second surface of the substrate, wherein the firstsurface is opposite the second surface. Note again that the coatingsneed not cover an entire surface.

Examples of conventional photochromic coatings include coatingscomprising any of the conventional photochromic compounds that arediscussed in detail below. For example, although not limiting herein,the photochromic coatings can be photochromic polyurethane coatings,such as those described in U.S. Pat. No. 6,187,444; photochromicaminoplast resin coatings, such as those described in U.S. Pat. Nos.4,756,973, 6,432,544 and 6,506,488; photochromic polysilane coatings,such as those described in U.S. Pat. No. 4,556,605; photochromicpoly(meth)acrylate coatings, such as those described in U.S. Pat. Nos.6,602,603, 6,150,430 and 6,025,026, and WIPO Publication WO 01/02449;polyanhydride photochromic coatings, such as those described in U.S.Pat. No. 6,436,525; photochromic polyacrylamide coatings such as thosedescribed in U.S. Pat. No. 6,060,001; photochromic epoxy resin coatings,such as those described in U.S. Pat. Nos. 4,756,973 and 6,268,055; andphotochromic poly(urea-urethane) coatings, such as those described inU.S. Pat. No. 6,531,076. The specifications of the aforementioned U.S.patents and international publications are hereby specificallyincorporated by reference herein.

Examples of linearly polarizing coatings include, but are not limitedto, coatings comprising conventional dichroic compounds such as, but notlimited to, those discussed above.

As used herein the term “transitional coating” means a coating that aidsin creating a gradient in properties between two coatings. For example,although not limiting herein, a transitional coating can aid in creatinga gradient in hardness between a relatively hard coating and arelatively soft coating. Examples of transitional coatings includeradiation-cured acrylate-based thin films.

Examples of protective coatings include abrasion-resistant coatingscomprising organo silanes, abrasion-resistant coatings comprisingradiation-cured acrylate-based thin films, abrasion-resistant coatingsbased on inorganic materials such as silica, titania and/or zirconia,organic abrasion-resistant coatings of the type that are ultravioletlight curable, oxygen barrier-coatings, UV-shielding coatings, andcombinations thereof. For example, according to one embodiment, theprotective coating can comprise a first coating of a radiation-curedacrylate-based thin film and a second coating comprising anorgano-silane. Examples of commercial protective coatings productsinclude SILVUE® 124 and HI-GARD® coatings, available from SDC Coatings,Inc. and PPG Industries, Inc., respectively.

Other embodiments disclosed herein provide an optical element comprisinga substrate and an at least partially aligned photochromic-dichroiccompound connected to the substrate and having an average absorptionratio greater than 2.3 in an activated state as determined according tothe CELL METHOD. Further, according to various embodiments disclosedherein, the absorption ratio of the at least partially alignedphotochromic-dichroic compound can range from 4 to 20, can further rangefrom 3 to 30, and can still further range from 2.5 to 50 or greater.

As previously discussed, the term “connected to” means in direct contactwith an object or indirect contact with an object through one or moreother structures, at least one of which is in direct contact with theobject. Thus, according to the above-mentioned embodiments, thephotochromic-dichroic compound connected to the substrate can be indirect contact with the substrate, or it can be in contact with one ormore other structures or materials that are in direct or indirectcontact with the substrate. For example, although not limiting herein,in one embodiment, the photochromic-dichroic compound can be present aspart of a coating or polymeric sheet that is in direct contact with theat least a portion of the substrate. In another embodiment, thephotochromic-dichroic compound can be present as part of a coating or asheet that is in direct contact with one or more other coatings orsheets, at least one of which is in direct contact with the substrate.

According to still other embodiments, the photochromic-dichroic compoundcan be contained in an at least partially ordered liquid crystalmaterial that is in direct (or indirect) contact with the substrate.Further, according to this embodiment, the optical element can comprisetwo substrates and the at least partially ordered liquid crystalmaterial containing the photochromic-dichroic compound can be positionedbetween the two substrates, for example, to form an active or a passiveliquid crystal cell.

In a still further non-limiting embodiment, the present inventioncomprises an optical element being a circular polarizer connected to asubstrate that is a packaging material for light-sensitive products.

Examples of photochromic-dichroic compounds suitable for used inconjunction with various embodiments disclosed herein include thecompounds listed below and the compounds described in U.S. Pat. No.7,256,921 in column 19, line 26 to column 22, line 47:

-   (1)    3-phenyl-3-(4-(4-(3-piperidin-4-yl-propyl)piperidino)phenyl)-13,13-dimethyl-indeno[2′,3′:3,4]-naphtho[1,2-b]pyran;-   (2)    3-phenyl-3-(4-(4-(3-(1-(2-hydroxyethyl)piperidin-4-yl)propyl)piperidino)phenyl)-13,13-dimethyl-indeno[2′,3′:3,4]naphtho[1,2-b]pyran;-   (3)    3-phenyl-3-(4-(4-(4-butyl-phenylcarbamoyl)-piperidin-1-yl)phenyl)-13,13-dimethyl-6-methoxy-7-(4-phenyl-piperazin-1-yl)indeno[2′,3′:3,4]naphtho[1,2-b]pyran;-   (4)    3-phenyl-3-(4-([1,4′]bipiperidinyl-1′-yl)phenyl)-13,13-dimethyl-6-methoxy-7-([1,4′]bipiperidinyl-1′-yl)indeno[2′,3′:3,4]naphtho[1,2-b]pyran;-   (5)    3-phenyl-3-(4-(4-phenyl-piperazin-1-yl)phenyl)-13,13-dimethyl-6-methoxy-7-(4-(4-hexylbenzoyloxy)-piperidin-1-yl)indeno[2′,3′:3,4]naphtho[1,2-b]pyran;    and-   (6)    3-phenyl-3-(4-(4-phenyl-piperazin-1-yl)phenyl)-13,13-dimethyl-6-methoxy-7-(4-(4′-octyloxy-biphenyl-4-carbonyloxy)-piperidin-1-yl)indeno[2′,3′:3,4]naphtho[1,2-b]pyran;

More generally, such photochromic-dichroic compounds comprise: (a) atleast one photochromic group (PC) chosen from pyrans, oxazines, andfulgides; and (b) at least one lengthening agent attached to thephotochromic group, wherein the lengthening agent (L) is represented bythe following Formula I (which is described in detail below):

—[S₁]_(c)-[Q₁-[S₂]_(d)]_(d′)-[Q₂-[S₃]_(e)]_(e′)-[Q₃-[S₄]_(f)]_(f′)—S₅—P  I

As used herein, the term “attached” means directly bonded to orindirectly bonded to through another group. Thus, for example, accordingto various embodiments disclosed herein, L can be directly bonded to PCas a substituent on PC, or L can be a substituent on another group (suchas a group represented by R¹, which is discussed below) that is directlybonded to PC (i.e., L is indirectly bonded to PC). Although not limitingherein, according to various embodiments, L can be attached to PC so asto extend or lengthen PC in an activated state such that the absorptionratio of the extended PC (i.e., the photochromic compound) is enhancedas compared to PC alone. Although not limiting herein, according tovarious embodiments, the location of attachment of L on PC can be chosensuch that L lengthens PC in at least one of a direction parallel to anda direction perpendicular to a theoretical transitional dipole moment ofthe activated form of PC. As used herein the term “theoreticaltransitional dipole moment” refers to transient dipolar polarizationcreated by interaction of electromagnetic radiation with the molecule.See, for example, IUPAC Compendium of Chemical Technology, 2^(nd) Ed.,International Union of Pure and Applied Chemistry (1997).

With reference to Formula I above, each Q₁, Q₂, and Q₃ can beindependently chosen for each occurrence from: a divalent group chosenfrom an unsubstituted or a substituted aromatic group, an unsubstitutedor a substituted alicyclic group, an unsubstituted or a substitutedheterocyclic group, and mixtures thereof, wherein substituents arechosen from: a group represented by P (as set forth below), liquidcrystal mesogens, halogen, poly(C₁-C₁₈ alkoxy), C₁-C₁₈ alkoxycarbonyl,C₁-C₁₈ alkylcarbonyl, C₁-C₁₈ alkoxycarbonyloxy, aryloxycarbonyloxy,perfluoro(C₁-C₁₈)alkoxy, perfluoro(C₁-C₁₈)alkoxycarbonyl,perfluoro(C₁-C₁₈)alkylcarbonyl, perfluoro(C₁-C₁₈)alkylamino,di-(perfluoro(C₁-C₁₈)alkyl)amino, perfluoro(C₁-C₁₈)alkylthio, C₁-C₁₈alkylthio, C₁-C₁₈ acetyl, C₃-C₁₀ cycloalkyl, C₃-C₁₀ cycloalkoxy, astraight-chain or branched C₁-C₁₈ alkyl group that is mono-substitutedwith cyano, halo, or C₁-C₁₈ alkoxy, or poly-substituted with halo, and agroup represented by one of the following formulae: -M(T)_((t-1)) and-M(OT)_((t-1)) wherein M is chosen from aluminum, antimony, tantalum,titanium, zirconium and silicon, T is chosen from organofunctionalradicals, organofunctional hydrocarbon radicals, aliphatic hydrocarbonradicals and aromatic hydrocarbon radicals, and t is the valence of M.As used herein, the prefix “poly” means at least two.

As discussed above, Q₁, Q₂, and Q₃ can be independently chosen for eachoccurrence from a divalent group, such as an unsubstituted or asubstituted aromatic group, unsubstituted or substituted heterocyclicgroup, and an unsubstituted or substituted alicyclic group. Examples ofuseful aromatic groups include: benzo, naphtho, phenanthro, biphenyl,tetrahydro naphtho, terphenyl, and anthraceno.

As used herein the term “heterocyclic group” means a compound having aring of atoms, wherein at least one atom forming the ring is differentthan the other atoms forming the ring. Further, as used herein, the termheterocyclic group specifically excludes fused heterocyclic groups.Examples of suitable heterocyclic groups from which Q₁, Q₂, and Q₃ canbe chosen include: isosorbitol, dibenzofuro, dibenzothieno, benzofuro,benzothieno, thieno, furo, dioxino, carbazolo, anthranilyl, azepinyl,benzoxazolyl, diazepinyl, dioazlyl, imidazolidinyl, imidazolyl,imidazolinyl, indazolyl, indoleninyl, indolinyl, indolizinyl, indolyl,indoxazinyl, isobenzazolyl, isoindolyl, isooxazolyl, isooxazyl,isopyrroyl, isoquinolyl, isothiazolyl, morpholino, morpholinyl,oxadiazolyl, oxathiazolyl, oxathiazyl, oxathiolyl, oxatriazolyl,oxazolyl, piperazinyl, piperazyl, piperidyl, purinyl, pyranopyrrolyl,pyrazinyl, pyrazolidinyl, pyrazolinyl, pyrazolyl, pyrazyl, pyridazinyl,pyridazyl, pyridyl, pyrimidinyl, pyrimidyl, pyridenyl, pyrrolidinyl,pyrrolinyl, pyrroyl, quinolizinyl, quinuclidinyl, quinolyl, thiazolyl,triazolyl, triazyl, N-arylpiperazino, aziridino, arylpiperidino,thiomorpholino, tetrahydroquinolino, tetrahydroisoquinolino, pyrryl,unsubstituted, mono- or di-substituted C₄-C₁₈ spirobicyclic amines, andunsubstituted, mono- or di-substituted C₄-C₁₈ spirotricyclic amines.

As discussed above, Q₁, Q₂, and Q₃ can be chosen from mono- ordi-substituted C₄-C₁₈ spirobicyclic amine and C₄-C₁₈ spirotricyclicamine. examples of suitable substituents include aryl, C₁-C₆ alkyl,C₁-C₆ alkoxy or phenyl (C₁-C₆)alkyl. Specific examples of mono- ordi-substituted spirobicyclic amines include:2-azabicyclo[2.2.1]hept-2-yl; 3-azabicyclo[3.2.1]oct-3-yl;2-azabicyclo[2.2.2]oct-2-yl; and 6-azabicyclo[3.2.2]nonan-6-yl. Specificexamples of mono- or di-substituted tricyclic amines include:2-azatricyclo[3.3.1.1 (3,7)]decan-2-yl; 4-benzyl-2-azatricyclo[3.3.1.1(3,7)]decan-2-yl; 4-methoxy-6-methyl-2-azatricyclo[3.3.1.1(3,7)]decan-2-yl; 4-azatricyclo[4.3.1.1(3,8)]undecan-4-yl; and7-methyl-4-azatricyclo[4.3.1.1 (3,8)]undecan-4-yl. Examples of alicyclicgroups from which Q₁, Q₂, and Q₃ can be chosen include, withoutlimitation, cyclohexyl, cyclopropyl, norbornenyl, decalinyl,adamantanyl, bicycloctane, per-hydrofluorene, and cubanyl.

With continued reference to Formula I, each S₁, S₂, S₃, S₄, and S₅ canbe independently chosen for each occurrence from a spacer unit chosenfrom:

(1) —(CH₂)_(g)—, —(CF₂)_(h)—, —Si(CH₂)_(g)—, —(Si[(CH₃)₂]O)_(h)—,wherein g is independently chosen for each occurrence from 1 to 20; h ischosen from 1 to 16;(2) —N(Z)-, —C(Z)=C(Z)-, —C(Z)═N—, —C(Z′)-C(Z′)- or a single bond,wherein Z is independently chosen for each occurrence from hydrogen,C₁-C₁₈ alkyl, C₃-C₁₀ cycloalkyl and aryl, and Z′ is independently chosenfor each occurrence from C₁-C₁₈ alkyl, C₃-C₁₀cycloalkyl and aryl; and(3) —O—, —C(O)—, —C≡C—, —N═N—, —S—, —S(O)—, —S(O)(O)—, —(O)S(O)O—,—O(O)S(O)O— or straight-chain or branched C₁-C₂₄ alkylene residue, saidC₁-C₂₄ alkylene residue being unsubstituted, mono-substituted by cyanoor halo, or poly-substituted by halo;provided that when two spacer units comprising heteroatoms are linkedtogether the spacer units are linked so that heteroatoms are notdirectly linked to each other and when S₁ and S₅ are linked to PC and P,respectively, they are linked so that two heteroatoms are not directlylinked to each other. As used herein the term “heteroatom” means atomsother than carbon or hydrogen.

Further, in Formula I, according to various embodiments, c, d, e, and feach can be independently chosen from an integer ranging from 1 to 20,inclusive; and d′, e′ and f′ each can be independently chosen from 0, 1,2, 3, and 4, provided that the sum of d′+e′+f′ is at least 1. Accordingto other embodiments, c, d, e, and f each can be independently chosenfrom an integer ranging from 0 to 20, inclusive; and d′, e′ and f′ eachcan be independently chosen from 0, 1, 2, 3, and 4, provided that thesum of d′+e′+f′ is at least 2. According to still other embodiments, c,d, e, and f each can be independently chosen from an integer rangingfrom 0 to 20, inclusive; and d′, e′ and f′ each can be independentlychosen from 0, 1, 2, 3, and 4, provided that the sum of d′+e′+f′ is atleast 3. According to still other embodiments, c, d, e, and f each canbe independently chosen from an integer ranging from 0 to 20, inclusive;and d′, e′ and f′ each can be independently chosen from 0, 1, 2, 3, and4, provided that the sum of d′+e′+f′ is at least 1.

Further, in Formula I, P can be chosen from: hydroxy, amino, C₂-C₁₈alkenyl, C₂-C₁₈ alkynyl, azido, silyl, siloxy, silylhydride,(tetrahydro-2H-pyran-2-yl)oxy, thio, isocyanato, thioisocyanato,acryloyloxy, methacryloyloxy, 2-(acryloyloxy)ethylcarbamyl,2-(methacryloyloxy)ethylcarbamyl, aziridinyl, allyloxycarbonyloxy,epoxy, carboxylic acid, carboxylic ester, acryloylamino,methacryloylamino, aminocarbonyl, C₁-C₁₈ alkyl aminocarbonyl,aminocarbonyl(C₁-C₁₈)alkyl, C₁-C₁₈ alkyloxycarbonyloxy, halocarbonyl,hydrogen, aryl, hydroxy(C₁-C₁₈)alkyl, C₁-C₁₈ alkyl, C₁-C₁₈ alkoxy,amino(C₁-C₁₈)alkyl, C₁-C₁₈ alkylamino, di-(C₁-C₁₈)alkylamino, C₁-C₁₈alkyl(C₁-C₁₈)alkoxy, C₁-C₁₈ alkoxy(C₁-C₁₈)alkoxy, nitro,poly(C₁-C₁₈)alkyl ether, (C₁-C₁₈)alkyl(C₁-C₁₈)alkoxy(C₁-C₁₈)alkyl,polyethyleneoxy, polypropyleneoxy, ethylenyl, acryloyl,acryloyloxy(C₁-C₁₈)alkyl, methacryloyl, methacryloyloxy(C₁-C₁₈)alkyl,2-chloroacryloyl, 2-phenylacryloyl, acryloyloxyphenyl,2-chloroacryloylamino, 2-phenylacryloylaminocarbonyl, oxetanyl,glycidyl, cyano, isocyanato(C₁-C₁₈)alkyl, itaconic acid ester, vinylether, vinyl ester, a styrene derivative, main-chain and side-chainliquid crystal polymers, siloxane derivatives, ethyleneiminederivatives, maleic acid derivatives, fumaric acid derivatives,unsubstituted cinnamic acid derivatives, cinnamic acid derivatives thatare substituted with at least one of methyl, methoxy, cyano and halogen,or substituted or unsubstituted chiral or non-chiral monovalent ordivalent groups chosen from steroid radicals, terpenoid radicals,alkaloid radicals and mixtures thereof, wherein the substituents areindependently chosen from C₁-C₁₈ alkyl, C₁-C₁₈ alkoxy, amino, C₃-C₁₀cycloalkyl, C₁-C₁₈ alkyl(C₁-C₁₈)alkoxy, fluoro(C₁-C₁₈)alkyl, cyano,cyano(C₁-C₁₈)alkyl, cyano(C₁-C₁₈)alkoxy or mixtures thereof, or P is astructure having from 2 to 4 reactive groups or P is an unsubstituted orsubstituted ring opening metathesis polymerization precursor.

Further, although not limiting herein, when P is a polymerizable group,the polymerizable group can be any functional group adapted toparticipate in a polymerization reaction. examples of polymerizationreactions include those described in the definition of “polymerization”in Hawley's Condensed Chemical Dictionary Thirteenth Edition, 1997, JohnWiley & Sons, pages 901-902, which disclosure is incorporated herein byreference. For example, although not limiting herein, polymerizationreactions include: “addition polymerization,” in which free radicals arethe initiating agents that react with the double bond of a monomer byadding to it on one side at the same time producing a new free electronon the other side; “condensation polymerization,” in which two reactingmolecules combine to form a larger molecule with elimination of a smallmolecule, such as a water molecule; and “oxidative couplingpolymerization.” Further, examples of polymerizable groups includehydroxy, acryloxy, methacryloxy, 2-(acryloxy)ethylcarbamyl,2-(methacryloxy)ethylcarbamyl, isocyanate, aziridine, allylcarbonate,and epoxy, e.g., oxiranylmethyl.

Moreover, P can be chosen from a main-chain or a side-chain liquidcrystal polymer and a liquid crystal mesogen. As used herein, the termliquid crystal “mesogen” means rigid rod-like or disc-like liquidcrystal molecules. Further, as used herein the term “main-chain liquidcrystal polymer” refers to a polymer having liquid crystal mesogenswithin the backbone (i.e., the main chain) structure of the polymer. Asused herein the term “side-chain liquid crystal polymer” refers to apolymer having liquid crystal mesogens attached to the polymer at theside chains. Although not limiting herein, generally, the mesogens aremade up of two or more aromatic rings that restrict the movement of aliquid crystal polymer. Examples of suitable rod-like liquid crystalmesogens include without limitation: substituted or unsubstitutedaromatic esters, substituted or unsubstituted linear aromatic compounds,and substituted or unsubstituted terphenyls. According to anotherspecific embodiment, P can be chosen from a steroid, for example andwithout limitation, a cholesterolic compound.

Examples of thermally reversible photochromic pyrans from which thephotochromic group PC can be chosen include benzopyrans, naphthopyrans,e.g., naphtho[1,2-b]pyrans, naphtho[2,1-b]pyrans, indeno-fusednaphthopyrans, such as those disclosed in U.S. Pat. No. 5,645,767, andheterocyclic-fused naphthopyrans, such as those disclosed in U.S. Pat.Nos. 5,723,072, 5,698,141, 6,153,126, and 6,022,497, which are herebyincorporated by reference; spiro-9-fluoreno[1,2-b]pyrans;phenanthropyrans; quinopyrans; fluoroanthenopyrans; spiropyrans, e.g.,spiro(benzindoline)naphthopyrans, spiro(indoline)benzopyrans,spiro(indoline)naphthopyrans, spiro(indoline)quinopyrans andspiro(indoline)pyrans. More specific examples of naphthopyrans and thecomplementary organic photochromic substances are described in U.S. Pat.No. 5,658,501, which are hereby specifically incorporated by referenceherein. Spiro(indoline)pyrans are also described in the text, Techniquesin Chemistry, Volume III, “Photochromism”, Chapter 3, Glenn H. Brown,Editor, John Wiley and Sons, Inc., New York, 1971, which is herebyincorporated by reference.

Examples of photochromic oxazines from which PC can be chosen includebenzoxazines, naphthoxazines, and spiro-oxazines, e.g.,spiro(indoline)naphthoxazines, spiro(indoline)pyridobenzoxazines,spiro(benzindoline)pyridobenzoxazines,spiro(benzindoline)naphthoxazines, spiro(indoline)benzoxazines,spiro(indoline)fluoranthenoxazine, and spiro(indoline)quinoxazine.examples of photochromic fulgides from which PC can be chosen include:fulgimides, and the 3-furyl and 3-thienyl fulgides and fulgimides, whichare disclosed in U.S. Pat. No. 4,931,220 (which are hereby specificallyincorporated by reference) and mixtures of any of the aforementionedphotochromic materials/compounds.

Further, wherein the photochromic-dichroic compound comprises at leasttwo PCs, the PCs can be linked to one another via linking groupsubstituents on the individual PCs. For example, the PCs can bepolymerizable photochromic groups or photochromic groups that areadapted to be compatible with a host material (“compatibilizedphotochromic group”). Examples of polymerizable photochromic groups fromwhich PC can be chosen and that are useful in conjunction with variousembodiments disclosed herein are disclosed in U.S. Pat. No. 6,113,814,which is hereby specifically incorporated by reference herein. Examplesof compatiblized photochromic groups from which PC can be chosen andthat are useful in conjunction with various embodiments disclosed hereinare disclosed in U.S. Pat. No. 6,555,028, which is hereby specificallyincorporated by reference herein.

Other suitable photochromic groups and complementary photochromic groupsare described in U.S. Pat. Nos. 6,080,338 at column 2, line 21 to column14, line 43; 6,136,968 at column 2, line 43 to column 20, line 67;6,296,785 at column 2, line 47 to column 31, line 5; 6,348,604 at column3, line 26 to column 17, line 15; 6,353,102 at column 1, line 62 tocolumn 11, line 64; and 6,630,597 at column 2, line 16 to column 16,line 23; the disclosures of the aforementioned patents are incorporatedherein by reference.

In addition to at least one lengthening agent (L), the photochromiccompounds can further comprise at least one group represented by R¹ thatis directly bonded to PC. Although not required, as previouslydiscussed, the at least one lengthening agent (L) can be indirectlybonded to PC through the at least one group represented by R¹. That is,L can be a substituent on at least one group R¹ that is bonded to PC.According to various embodiments disclosed herein, R¹ can beindependently chosen for each occurrence from substituents disclosed inU.S. Pat. No. 7,256,921 from column 26, line 60 to column 30, line 64.The photochromic-dichroic compounds of the present invention include thecompounds and methods of preparation disclosed in U.S. Pat. No.7,256,921 from column 30, line 65 to column 66, line 60.

As previously discussed, one embodiment disclosed herein provides anoptical element comprising a substrate and at least one at leastpartially aligned photochromic-dichroic compound connected to at least aportion of the substrate and having an average absorption ratio greaterthan 2.3 in an activated state as determined according to the CELLMETHOD. Additionally, according to this embodiment, the optical elementcan further comprise at least one orientation facility having a at leasta first general direction connected to at least a portion of thesubstrate, and at least a portion of the at least one at least partiallyaligned photochromic-dichroic compound can be at least partially alignedby interaction with the orientation facility.

As used herein the term “orientation facility” means a mechanism thatcan facilitate the positioning of one or more other structures that areexposed, directly and/or indirectly, to at least a portion thereof. Asused herein the term “order” means bring into a suitable arrangement orposition, such as aligning with another structure or material, or bysome other force or effect. Thus, as used herein the term “order”encompasses both contact methods of ordering a material, such as byaligning with another structure or material, and non-contact methods ofordering a material, such as by exposure to an external force or effect.The term order also encompasses combinations of contact and non-contactmethods.

For example, in one embodiment, the portion of the partially alignedphotochromic-dichroic compound that is at least partially aligned byinteraction with the orientation facility can be at least partiallyaligned such that the long-axis of the photochromic-dichroic compound inthe activated state is essentially parallel to the first generaldirection of the orientation facility. According to another embodiment,the portion of the partially aligned photochromic-dichroic compound thatis at least partially aligned by interaction with a portion of theorientation facility is bound to or reacted with the portion of theorientation facility. As used herein with reference to order oralignment of a material or structure, the term “general direction”refers to the predominant arrangement or orientation of the material,compound or structure. Further, it will be appreciated by those skilledin the art that a material, compound or structure can have a generaldirection even though there is some variation within the arrangement ofthe material, compound or structure, provided that the material,compound or structure has at least one predominate arrangement.

As discussed above, the orientation facilities according to variousembodiments disclosed herein can have at least a first generaldirection. For example, the orientation facility can comprise a firstordered region having a first general direction and at least one secondordered region adjacent the first ordered region having a second generaldirection that is different from the first general direction. Further,the orientation facility can have a plurality of regions, each of whichhas a general direction that is the same or different from the remainingregions so as to form a desired pattern or design. Additionally, the atleast one orientation facility can comprise one or more different typesof orientation facilities. Examples of orientation facilities that canbe used in conjunction with this and other embodiments disclosed hereininclude at least partial coatings comprising an at least partiallyordered alignment medium, at least partially ordered polymer sheets, atleast partially treated surfaces, Langmuir-Blodgett films, andcombinations thereof.

For example, although not limiting herein, according to one embodiment,the orientation facility can comprise a coating comprising an at leastpartially ordered alignment medium. Examples of suitable alignment mediathat can be used in conjunction with various embodiments disclosedherein include photo-orientation materials, rubbed-orientationmaterials, and liquid crystal materials. Methods of ordering at least aportion of the alignment medium are described herein below in detail.

As discussed above, according to various embodiments, the alignmentmedium can be a liquid crystal material. Liquid crystal materials,because of their structure, are generally capable of being ordered oraligned so as to take on a general direction. More specifically, becauseliquid crystal molecules have rod- or disc-like structures, a rigid longaxis, and strong dipoles, liquid crystal molecules can be ordered oraligned by interaction with an external force or another structure suchthat the long axis of the molecules takes on an orientation that isgenerally parallel to a common axis. For example, although not limitingherein, it is possible to align the molecules of a liquid crystalmaterial with a magnetic field, an electric field, linearly polarizedinfrared radiation, linearly polarized ultraviolet radiation, linearlypolarized visible radiation, or shear forces. It is also possible toalign liquid crystal molecules with an oriented surface. That is, liquidcrystal molecules can be applied to a surface that has been oriented,for example by rubbing, grooving, or photo-alignment methods, andsubsequently aligned such that the long axis of each of the liquidcrystal molecules takes on an orientation that is generally parallel tothe general direction of orientation of the surface. Examples of liquidcrystal materials suitable for use as alignment media according tovarious embodiments disclosed herein include liquid crystal polymers,liquid crystal pre-polymers, liquid crystal monomers, and liquid crystalmesogens. As used herein the term “pre-polymer” means partiallypolymerized materials.

Liquid crystal monomers that are suitable for use in conjunction withvarious embodiments disclosed herein include mono- as well asmulti-functional liquid crystal monomers. Further, according to variousembodiments disclosed herein, the liquid crystal monomer can be across-linkable liquid crystal monomer, and can further be aphotocross-linkable liquid crystal monomer. As used herein the term“photocross-linkable” means a material, such as a monomer, a pre-polymeror a polymer that can be cross-linked on exposure to actinic radiation.For example, photocross-linkable liquid crystal monomers include thoseliquid crystal monomers that are cross-linkable on exposure toultraviolet radiation and/or visible radiation, either with or withoutthe use of polymerization initiators.

Examples of cross-linkable liquid crystal monomers suitable for use inaccordance with various embodiments disclosed herein include liquidcrystal monomers having functional groups chosen from acrylates,methacrylates, allyl, allyl ethers, alkynes, amino, anhydrides,epoxides, hydroxides, isocyanates, blocked isocyanates, siloxanes,thiocyanates, thiols, urea, vinyl, vinyl ethers and blends thereof.Examples of photocross-linkable liquid crystal monomers suitable for usein the coatings of the alignment facilities according to variousembodiments disclosed herein include liquid crystal monomers havingfunctional groups chosen from acrylates, methacrylates, alkynes,epoxides, thiols, and blends thereof.

Liquid crystal polymers and pre-polymers that are suitable for use inconjunction with various embodiments disclosed herein include main-chainliquid crystal polymers and pre-polymers and side-chain liquid crystalpolymers and pre-polymers. In main-chain liquid crystal polymers andpre-polymers, rod- or disc-like liquid crystal mesogens are primarilylocated within the polymer backbone. In side-chain polymers andpre-polymers, the rod- or disc-like liquid crystal mesogens primarilyare located within the side chains of the polymer. Additionally,according to various embodiments disclosed herein, the liquid crystalpolymer or pre-polymer can be cross-linkable, and further can bephotocross-linkable.

Examples of liquid crystal polymers and pre-polymers that are suitablefor use in accordance with various embodiments disclosed herein include,but are not limited to, main-chain and side-chain polymers andpre-polymers having functional groups chosen from acrylates,methacrylates, allyl, allyl ethers, alkynes, amino, anhydrides,epoxides, hydroxides, isocyanates, blocked isocyanates, siloxanes,thiocyanates, thiols, urea, vinyl, vinyl ethers, and blends thereof.Examples of photocross-linkable liquid crystal polymers and pre-polymersthat are suitable for use in the coatings of the alignment facilitiesaccording to various embodiments disclosed herein include those polymersand pre-polymers having functional groups chosen from acrylates,methacrylates, alkynes, epoxides, thiols, and blends thereof.

Liquid crystals mesogens that are suitable for use in conjunction withvarious embodiments disclosed herein include thermotropic liquid crystalmesogens and lyotropic liquid crystal mesogens. Further, examples ofliquid crystal mesogens that are suitable for use in conjunction withvarious embodiments disclosed herein include columatic (or rod-like)liquid crystal mesogens and discotic (or disc-like) liquid crystalmesogens.

Examples of photo-orientation materials that are suitable for use as analignment medium in conjunction with various embodiments disclosedinclude photo-orientable polymer networks. Specific examples of suitablephoto-orientable polymer networks include azobenzene derivatives,cinnamic acid derivatives, coumarine derivatives, ferulic acidderivatives, and polyimides. For example, according to one embodiment,the orientation facility can comprise at least one at least partialcoating comprising an at least partially ordered photo-orientablepolymer network chosen from azobenzene derivatives, cinnamic acidderivatives, coumarine derivatives, ferulic acid derivatives, andpolyimides. Specific examples of cinnamic acid derivatives that can beused as an alignment medium in conjunction with various embodimentsdisclosed herein include polyvinyl cinnamate and polyvinyl esters ofparamethoxycinnamic acid.

As used herein the term “rubbed-orientation material” means a materialthat can be at least partially ordered by rubbing at least a portion ofa surface of the material with another suitably textured material. Forexample, although not limiting herein, in one embodiment, therubbed-orientation material can be rubbed with a suitably textured clothor a velvet brush. Examples of rubbed-orientation materials that aresuitable for use as an alignment medium in conjunction with variousembodiments disclosed herein include (poly)imides, (poly)siloxanes,(poly)acrylates, and (poly)coumarines. Thus, for example, although notlimiting herein, the coating comprising the alignment medium can be acoating comprising a polyimide that has been rubbed with velvet or acloth so as to at least partially order at least a portion of thesurface of the polyimide.

As discussed above, the at least one orientation facility according tocertain embodiments disclosed herein can comprise an at least partiallyordered polymer sheet. For example, although not limiting herein, asheet of polyvinyl alcohol can be at least partially ordered bystretching the sheet, and there after the sheet can be bonded to the atleast a portion a surface of the optical substrate to form theorientation facility. Alternatively, the ordered polymer sheet can bemade by a method that at least partially orders the polymer chainsduring fabrication, for example and without limitation, by extrusion.Further, the at least partially ordered polymer sheet can be formed bycasting or otherwise forming a sheet of a liquid crystal material andthereafter at least partially ordering the sheet for example, butexposing the sheet to at least one of a magnetic field, an electricfield, or a shear force. Still further, the at least partially orderedpolymer sheet can be made using photo-orientation methods. For exampleand without limitation, a sheet of a photo-orientation material can beformed, for example by casting, and thereafter at least partiallyordered by exposure to linearly polarized ultraviolet radiation. Stillother methods of forming at least partially ordered polymer sheets aredescribed herein below.

Still further, the orientation facilities according to variousembodiments disclosed herein can comprise an at least partially treatedsurface. As used herein, the term “treated surface” refers to at least aportion of a surface that has been physically altered to create at leastone ordered region on least a portion of the surface. Examples of atleast partially treated surfaces include at least partially rubbedsurfaces, at least partially etched surfaces, and at least partiallyembossed surfaces. Further, the at least partially treated surfaces canbe patterned, for example using a photolithographic or aninterferographic process. Examples of at least partially treatedsurfaces that are useful in forming the orientation facilities accordingto various embodiments disclosed herein include, chemically etchedsurfaces, plasma etched surfaces, nanoetched surfaces (such as surfacesetched using a scanning tunneling microscope or an atomic forcemicroscope), laser etched surfaces, and electron-beam etched surfaces.

In one specific embodiment, wherein the orientation facility comprisesan at least partially treated surface, imparting the orientationfacility can comprise depositing a metal salt (such as a metal oxide ormetal fluoride) onto at least a portion of a surface, and thereafteretching the deposit to form the orientation facility. Examples ofsuitable techniques for depositing a metal salt include plasma vapordeposition, chemical vapor deposition, and sputtering. Examples ofetching processes are set forth above.

As used herein the term “Langmuir-Blodgett films” means one or more atleast partially ordered molecular films on a surface. For example,although not limiting herein, a Langmuir-Blodgett film can be formed bydipping a substrate into a liquid one or more times so that it is atleast partially covered by a molecular film and then removing thesubstrate from the liquid such that, due to the relative surfacetensions of the liquid and the substrate, the molecules of the molecularfilm are at least partially ordered in a general direction. As usedherein, the term molecular film refers to monomolecular films (i.e.,monolayers) as well as films comprising more than one monolayer.

In addition to the orientation facilities described above, the opticalelements according to various embodiments disclosed herein can furthercomprise at least one coating comprising an at least partially orderedalignment transfer material interposed between the orientation facilityand the photochromic-dichroic compound (or coating comprising the same).Still further, the optical elements can comprise a plurality of coatingscomprising an alignment transfer interposed between the orientationfacility and the photochromic-dichroic compound. For example, althoughnot limiting herein, the optical element can comprise at least oneorientation facility comprising a coating comprising an at leastpartially ordered alignment medium connected to the optical substrate,and a coating comprising an at least partially ordered alignmenttransfer material connected to the orientation facility. Further,according to this embodiment, the photochromic-dichroic compound can beat least partially aligned by interaction with the alignment transfermaterial. More specifically, although not limiting herein, in oneembodiment, at least a portion of the alignment transfer material can bealigned by interaction with at least a portion of the alignment medium,and at least a portion of the photochromic-dichroic compound can bealigned by interaction with the at least a partially aligned portion ofthe alignment transfer material. That is, the alignment transfermaterial can facilitate the propagation or transfer of a suitablearrangement or position from the orientation facility to thephotochromic-dichroic compound.

Examples of alignment transfer materials that are suitable for use inconjunction with various embodiments disclosed herein include, withoutlimitation, those liquid crystal materials described above in connectionwith the alignment media disclosed herein. As previously discussed, itis possible to align the molecules of a liquid crystal material with anoriented surface. That is, a liquid crystal material can be applied to asurface that has been oriented and subsequently aligned such that thelong axis of the liquid crystal molecules takes on an orientation thatis generally parallel to the general direction of orientation of thesurface. Thus, according to various embodiments disclosed herein whereinthe alignment transfer material comprises a liquid crystal material, theliquid crystal material can be at least partially ordered by aligningthe at least a portion of the liquid crystal material with at least aportion of the orientation facility such that the long axis of themolecules of at least a portion of the liquid crystal material aregenerally parallel to at least a first general direction of theorientation facility. In this manner, the general direction of theorientation facility can be transferred to the liquid crystal material,which in turn can transfer the general direction to another structure ormaterial. Further, if the at least one orientation facility comprises aplurality of regions having general directions that together form adesign or pattern (as previously described), that design or pattern canbe transferred to the liquid crystal material by aligning the liquidcrystal material with the various regions of the orientation facility asdiscussed above. Additionally, although not required, according tovarious embodiments disclosed herein, at least a portion of the liquidcrystal material can be exposed to at least one of: a magnetic field, anelectric field, linearly polarized infrared radiation, linearlypolarized ultraviolet radiation, and linearly polarized visibleradiation while being at least partially aligned with the orientationfacility.

Still further, in addition to the at least partially alignedphotochromic-dichroic compound connected to the substrate, the opticalelement according to various embodiments disclosed herein can comprisean at least partially ordered anisotropic material connected to thesubstrate. That is, according to certain embodiments the optical elementcomprises a substrate, an at least partially alignedphotochromic-dichroic compound connected to the substrate, thephotochromic-dichroic compound having an average absorption ratiogreater than 2.3 in an activated state as determined according to theCELL METHOD, and an anisotropic material connected to the substrate.

As used herein the term “anisotropic” means having at least one propertythat differs in value when measured in at least one different direction.Thus, “anisotropic materials” are materials that have at least oneproperty that differs in value when measured in at least one differentdirection. Examples of anisotropic materials that are suitable for usein conjunction with various embodiments disclosed herein include,without limitation, those liquid crystal materials described above.

According to various embodiments, the photochromic-dichroic compound canbe aligned by interaction with the anisotropic material. For example,although not limiting herein, at least a portion of thephotochromic-dichroic compound can be aligned such that the long-axis ofthe photochromic-dichroic compound in the dichroic state is essentiallyparallel to the general direction of the anisotropic material. Further,although not required, the photochromic-dichroic compound can be boundto or reacted with the anisotropic material.

Further, according to various embodiments disclosed herein, thephotochromic-dichroic compound and the anisotropic material can bepresent as a coating on the substrate. For example, according to oneembodiment, the anisotropic material can be a liquid crystal material,and the photochromic-dichroic compound and anisotropic material can bepresent as a liquid crystal coating on the substrate. According toanother embodiment, the coating can be a phase-separated polymer coatingcomprising a matrix phase and a guest phase distributed in the matrixphase. Although not limiting herein, according to this embodiment, thematrix phase can comprise an at least partially ordered liquid crystalpolymer. Further, according to this embodiment, the guest phase cancomprise the anisotropic material and at least a portion of thephotochromic-dichroic compound. Still further, as discussed above, thephotochromic-dichroic compound can be at least partially aligned byinteraction with the anisotropic material.

In another embodiment, the coating can comprise an interpenetratingpolymer network. According to this embodiment, the anisotropic materialand a polymeric material can form an interpenetrating polymer network,wherein at least a portion of the polymeric material interpenetrateswith the anisotropic material. As used herein the term “interpenetratingpolymer network” means an entangled combination of polymers, at leastone of which is cross-linked, that are not bonded to each other. Thus,as used herein, the term interpenetrating polymer network includessemi-interpenetrating polymer networks. For example, see L. H. Sperling,Introduction to Physical Polymer Science, John Wiley & Sons, New York(1986) at page 46. Further, according to this embodiment, at least aportion of the photochromic-dichroic compound can be aligned with theanisotropic material. Still further, according to this embodiment, thepolymeric material can be isotropic or anisotropic, provided that, onthe whole, the coating is anisotropic. Methods of forming such coatingsare described in more detail herein below.

Still other embodiments disclosed herein provide an optical elementcomprising a substrate, an at least partially ordered orientationfacility connected to the substrate, and a coating connected to theorientation facility, the coating comprising an anisotropic materialthat is at least partially aligned with the ordered orientation facilityand a photochromic-dichroic compound that is at least partially alignedwith the anisotropic material.

As previously discussed, the orientation facilities according to variousembodiments disclosed herein can comprise a first ordered region havinga first general direction and at least one second ordered regionadjacent the first region having a second general direction that isdifferent from the first general direction. Further, the orientationfacility can comprise multiple ordered regions having multiple generaldirections that together create a specific design or pattern. Examplesof orientation facilities that are suitable for use in conjunction withthis embodiment are described above in detail. Additionally, accordingto various embodiments disclosed herein, a coating comprising analignment transfer material can be positioned between the orientationfacility and the coating comprising the anisotropic material and thephotochromic-dichroic compound. Further, the general direction orpattern of the orientation facility can be transferred to the alignmenttransfer material by alignment, which, in turn, can transfer the generaldirection of the orientation facility to the coating comprising theanisotropic material and the photochromic-dichroic compound byalignment. That is, the anisotropic material of the coating can bealigned with the alignment transfer material. Further, thephotochromic-dichroic compound can be at least partially aligned byinteraction with the anisotropic material.

Further, according to various embodiments disclosed herein, theanisotropic material can be adapted to allow the photochromic-dichroiccompound to switch from a first state to the second state at a desiredrate. Generally speaking conventional photochromic compounds can undergoa transformation from one isomeric form to another in response toactinic radiation, with each isomeric form having a characteristicabsorption spectrum. The photochromic-dichroic compounds according tovarious embodiments disclosed herein undergo a similar isomerictransformation. The rate or speed at which this isomeric transformation(and the reverse transformation) occurs depends, in part, upon theproperties of the local environment surrounding thephotochromic-dichroic compound (that is, the “host”). Although notlimiting herein, it is believed by the inventors the rate oftransformation of the photochromic-dichroic compound will depend, inpart, upon the flexibility of the chain segments of the host, that is,the mobility or viscosity of the chain segments of the host. Inparticular, while not limiting herein, it is believed that the rate oftransformation of the photochromic-dichroic compound will generally befaster in hosts having flexible chain segments than in host having stiffor rigid chain segments. Therefore, according to certain embodimentsdisclosed herein, wherein the anisotropic material is a host, theanisotropic material can be adapted to allow the photochromic-dichroiccompound to transform between various isomeric states at desired rates.For example, although not limiting herein, the anisotropic material canbe adapted by adjusting one or more of the molecular weight and thecross-link density of the anisotropic material.

According to another embodiment, the coating comprising an anisotropicmaterial and a photochromic-dichroic compound can be a phase-separatedpolymer coating comprising matrix phase, for example and withoutlimitation, a liquid crystal polymer, and guest phase distributed withinthe matrix phase. Further, according to this embodiment, the guest phasecan comprise the anisotropic material. Still further, according to thisembodiment, the majority of the photochromic-dichroic compound can becontained within the guest phase of the phase-separated polymer coating.As previously discussed, because the transformation rate of thephotochromic-dichroic compound depends, in part, on the host in which itis contained, according to this embodiment, the rate of transformationof the photochromic-dichroic compound will depend, largely, on theproperties of the guest phase.

For example, one embodiment provides an optical element comprising asubstrate, at least one orientation facility connected to the substrate,and a coating connected to the orientation facility and comprising aphase-separated polymer. According to this embodiment, thephase-separated polymer can comprise a matrix phase, at least a portionof which is at least partially aligned with the orientation facility,and a guest phase comprising an anisotropic material dispersed withinthe matrix phase. Further according to this embodiment, at least aportion of the anisotropic material of the guest phase can be at leastpartially aligned with the orientation facility and aphotochromic-dichroic compound can be at least partially aligned withthe anisotropic material. Still further, according to variousembodiments disclosed herein, the matrix phase of the phase-separatedpolymer can comprise a liquid crystal polymer, and the anisotropicmaterial of the guest phase can be chosen from liquid crystal polymersand liquid crystal mesogens. Examples of such materials are set forth indetail above. Additionally, while not limiting herein, according to thisembodiment, the coating comprising the phase-separated polymer can besubstantially haze-free. Haze is defined as the percentage oftransmitted light that deviates from the incident beam by more than 2.5degrees on average according to ASTM D 1003 Standard Test Method of Hazeand Luminous Transmittance of Transparent Plastics. An example of aninstrument on which haze measurements according to ASTM D 1003 can bemade is Haze-Gard Plus™ made by BYK-Gardener.

Further, although not limiting herein, according to other embodimentsthe photochromic-dichroic compound can be encapsulated or coated with anat least partially ordered host material and then the encapsulated orcoated photochromic-dichroic compound can be dispersed within anothermaterial. For example, although not limiting herein, thephotochromic-dichroic compound can be encapsulated or overcoated with anat least partially ordered anisotropic material having relativelyflexible chain segments, such as a liquid crystal material, andthereafter dispersed or distributed in another material havingrelatively rigid chain segments. For example, the encapsulatedphotochromic-dichroic compound can be dispersed or distributed in aliquid crystal polymer having relatively rigid chain segments andthereafter the mixture can be applied to a substrate to form a coating.

According to still another embodiment, the coating comprising ananisotropic material and a photochromic-dichroic compound can be aninterpenetrating polymer network coating. For example, the coating cancomprise a polymeric material that interpenetrates with the anisotropicmaterial, and the photochromic-dichroic compound can be at leastpartially aligned with the anisotropic material. Methods of forming suchinterpenetrating network coatings are described below in more detail.

Still other embodiments disclosed herein provide an optical elementcomprising a substrate, a first coating comprising an at least partiallyordered alignment medium connected the substrate, a second coatingcomprising an alignment transfer material connected to and at leastpartially aligned with the alignment medium, and a third coatingconnected to the alignment transfer material, the third coatingcomprising an anisotropic material that is at least partially alignedwith the alignment transfer material and a photochromic-dichroiccompound that is at least partially aligned with the anisotropicmaterial.

Although not limiting herein, according to various embodiments, thefirst coating comprising the at least partially ordered alignment mediumcan have a thickness that varies widely depending upon the finalapplication and/or the processing equipment employed. For example, inone embodiment, the thickness of the coating can range from at least 0.5nanometers to 10,000 nanometers. In another embodiment, the coating canhave a thickness ranging from at least 0.5 nanometers to 1000nanometers. In still another embodiment, the coating can have athickness ranging from at least 2 nanometers to 500 nanometers. In yetanother embodiment, the coating can have a thickness ranging from 100nanometers to 500 nanometers. Additionally, according to variousembodiments, the optical element can comprise a plurality of coatingscomprising an at least partially ordered alignment medium. Further eachof the coatings can have the same or a different thickness as the othercoatings of the plurality.

Further, according to various embodiments disclosed herein, the secondcoating comprising the alignment transfer material can have a thicknessthat varies widely depending upon the final application and/or theprocessing equipment employed. For example, the thickness of the coatingcomprising the at least partially ordered alignment transfer materialcan range from 0.5 microns to 1000 microns. In another embodiment, thecoating can have a thickness ranging from 1 to 25 microns. In stillanother embodiment, the coating can have a thickness ranging from 5 to20 microns. Additionally, according to various embodiments, the opticalelement can comprise a plurality of coatings comprising an alignmenttransfer material. Further each of the plurality of coatings can havethe same or a different thickness as the other coatings of theplurality.

Still further, according to various embodiments disclosed herein, thethird at least partial coating comprising the anisotropic material andthe photochromic-dichroic compound can have a thickness that varieswidely depending upon the final application and/or the processingequipment employed. In one embodiment, the coating comprising the atleast partially aligned anisotropic material and the\photochromic-dichroic compound can have a thickness of at least 0.5microns to 1000 microns. According to other embodiments, the thirdcoating can have a thickness ranging from 1 micron to 25 microns.According to still other embodiments, the third coating can have athickness ranging from 5 microns to 20 microns. Additionally, accordingto various embodiments, the optical element can comprise a plurality ofsuch coatings, and each of the coatings can have the same or a differentthickness as the other coatings of the plurality. Examples of suitablephotochromic-dichroic compounds are described above in detail.

Further, according to various embodiments, in addition to the thirdcoating, either or both of the first and second coatings can comprisephotochromic-dichroic compounds that are the same or different from thephotochromic-dichroic compounds of the third coating. Still further,according to various embodiments, any of the coatings described abovecan further comprise at least one additive, at least one conventionaldichroic compound and/or at least one conventional photochromiccompound. Examples of suitable additives, conventional dichroiccompounds, and conventional photochromic compounds are set forth above.Further, as previously discussed, in addition to the first, second, andthird coatings described above, the optical elements according tovarious embodiments disclosed herein can further comprise primercoatings, anti-reflective coatings, photochromic coatings, linearlypolarizing coatings, circularly polarizing coatings, ellipticallypolarizing coatings, transitional coatings, and protective coatings.Examples of such coatings are provided above.

Other embodiments disclosed herein provide a composite optical elementcomprising a substrate, an at least partially ordered polymeric sheetconnected to the substrate, and an at least partially alignedphotochromic-dichroic compound connected to the polymeric sheet andhaving an average absorption ratio greater than 2.3 in an activatedstate as determined according to the CELL METHOD. For example, althoughnot limiting herein, according to one embodiment a stretched polymersheet containing at least one photochromic-dichroic compound that is atleast partially aligned by the oriented polymer chains of the stretchedpolymer sheet can be connected to the substrate.

Further, according to various embodiments, the composite optical elementcan comprise a plurality of polymeric sheets, at least one of which isat least partially ordered, connected to the substrate. For example,although not limiting herein, the composite optical element can comprisea substrate and an at least partially ordered polymeric sheet comprisingan at least partially aligned photochromic-dichroic compound thatinterposed between two dimensionally stable or “rigid” polymer sheetsconnected to the substrate. According to other embodiments, thecomposite optical element can comprise two or more at least partiallyordered polymeric sheets comprising an at least partially alignedphotochromic-dichroic compound that are connected to the substrate.Further, the two or more at least partially ordered polymeric sheets canhave the same general direction or different general directions and cancomprise the same photochromic-dichroic compound or differentphotochromic-dichroic compounds. Still further, the polymeric sheets canbe stacked or layered on the substrate or they can be positionedadjacent each other on the substrate.

Examples of polymeric sheets that can be used in conjunction with thisembodiment include, without limitation, stretched polymer sheets,ordered liquid crystal polymer sheets, and photo-oriented polymersheets. Examples of polymeric materials, other than liquid crystalmaterials and photo-orientation materials that can be used in formingpolymeric sheets according to various embodiments disclosed hereininclude without limitation: polyvinyl alcohol, polyvinyl chloride,polyurethane, polyacrylate, and polycaprolactam. Examples of methods ofordering polymeric sheets are described below in more detail.

Still other embodiments disclosed herein provide a composite opticalelement comprising a substrate and at least one sheet connected to thesubstrate, the sheet comprising: an at least partially ordered liquidcrystal polymer having at least a first general direction, an at leastpartially ordered liquid crystal material having a second generaldirection distributed within the liquid crystal polymer, and aphotochromic-dichroic compound that is at least partially aligned withthe liquid crystal material, wherein the second general direction isgenerally parallel to the first general direction.

The optical elements of the present invention further comprise abirefringent layer (b) connected to the photochromic linear polarizingelement. The birefringent layer is operable to circularly orelliptically polarize transmitted radiation. When a circular polarizingelement is desired, the birefringent layer comprises a quarter-waveplate. The birefringent layer, also called a compensation plate or layeror a retardation plate or layer, may be composed of one sheet or may bea multiple layer structure of two or more.

In certain embodiments of the present invention, the birefringent layer(b) comprises a layer having a first ordered region having a firstgeneral direction, and at least one second ordered region adjacent thefirst ordered region having a second general direction that is the sameor different from the first general direction so as to form a desiredpattern in the layer.

The material used to prepare the birefringent layer is not particularlylimited, and may be any birefringent material known in the art. Forexample, a polymer film, a liquid crystal film, self-assemblingmaterials, or a film in which a liquid crystal material is aligned canbe used. Examples of particular birefringent layers include thosedescribed in U.S. Pat. No. 6,864,932 at column 3, line 60 to column 4,line 64; U.S. Pat. No. 5,550,661 at column 4, line 30 to column 7, line2; U.S. Pat. No. 5,948,487 at column 7, line 1 to column 10, line 10,each of which is incorporated herein by reference.

Examples of specific birefringent films include film Model No. NRF-140,a positively birefringent, uniaxial film available from NittoCorporation, Japan, or Nitto Denko America, Inc., New Brunswick, N.J.Also suitable are OPTIGRAFIX circular polarizer films, available fromGRAFIX Plastics, a division of GRAFIX, Inc., Cleveland, Ohio.

Specific polymeric sheets used to prepare the birefringent layer (b) maycomprise polyacrylates, polymethacrylates, poly(C₁-C₁₂) alkylmethacrylates, polyoxy(alkylene methacrylates), poly (alkoxylated phenolmethacrylates), cellulose acetate, cellulose triacetate, celluloseacetate propionate, cellulose acetate butyrate, poly(vinyl acetate),poly(vinyl alcohol), poly(vinyl chloride), poly(vinylidene chloride),poly(vinylpyrrolidone), poly((meth)acrylamide), poly(dimethylacrylamide), poly(hydroxyethyl methacrylate), poly((meth)acrylic acid),thermoplastic polycarbonates, polyesters, polyurethanes,polythiourethanes, poly(ethylene terephthalate), polystyrene, poly(alphamethylstyrene), copoly(styrene-methylmethacrylate),copoly(styrene-acrylonitrile), polyvinylbutyral and polymers of membersof the group consisting of polyol(allyl carbonate)monomers,mono-functional acrylate monomers, mono-functional methacrylatemonomers, polyfunctional acrylate monomers, polyfunctional methacrylatemonomers, diethylene glycol dimethacrylate monomers, diisopropenylbenzene monomers, alkoxylated polyhydric alcohol monomers anddiallylidene pentaerythritol monomers; and in particular self-assemblingmaterials, polycarbonate, polyamide, polyimide, poly(meth)acrylate,polycyclic alkene, polyurethane, poly(urea)urethane, polythiourethane,polythio(urea)urethane, polyol(allyl carbonate), cellulose acetate,cellulose diacetate, cellulose triacetate, cellulose acetate propionate,cellulose acetate butyrate, polyalkene, polyalkylene-vinyl acetate,poly(vinylacetate), poly(vinyl alcohol), poly(vinyl chloride),poly(vinylformal), poly(vinylacetal), poly(vinylidene chloride),poly(ethylene terephthalate), polyester, polysulfone, polyolefin,copolymers thereof, and/or mixtures thereof.

The birefringent layer (b) may be applied to the photochromic linearlypolarizing element in such a way that a slow axis direction (directionwhere a refractive index is largest in a plane) of the birefringentlayer is oriented with respect to an alignment direction of thepolarizer to yield the desired resultant polarization; i.e., circular orelliptical. For example, a quarter-wave plate would be oriented at anangle of 45°+/−5° with respect to an alignment direction of thephotochromic dye of the polarizer, and often 45°+/−3°.

Alternatively, the resultant polarization of the optical element may bedetermined by setting the thickness of the birefringent layer. Forexample, to yield a circular polarizing element, the thickness of thebirefringent layer is such that the emerging refracted rays of light areout of phase by one-quarter wavelength.

Embodiments of methods of making optical elements and devices will nowbe described. One embodiment provides a method of making an opticalelement comprising forming a coating comprising an at least partiallyaligned photochromic-dichroic compound on a substrate. As used hereinthe term “on” means in direct contact with an object (such as asubstrate) or in indirect contact with the object through one or moreother coatings or structures, at least one of which is in direct contactwith the object. Further, according to this embodiment, in addition tothe photochromic-dichroic compound, an at least partially orderedanisotropic material can be connected to the substrate.

According to this embodiment, the coating can have an average absorptionratio of at least 1.5. Further, according to this and other embodimentsof methods of making elements and devices disclosed herein, thephotochromic-dichroic compound can have an average absorption ratiogreater than 2.3 in an activated state as determined according to theCELL METHOD. Examples of photochromic-dichroic compounds that are usefulin conjunction with the methods of making elements and devices disclosedherein are set forth above in detail.

According to various embodiments disclosed herein, forming the coatingcomprising the photochromic-dichroic compound can comprise applying thephotochromic-dichroic compound and an anisotropic material to thesubstrate, at least partially ordering the anisotropic material, and atleast partially aligning the photochromic-dichroic compound with theanisotropic material. Methods of applying the photochromic-dichroiccompound and the anisotropic material to the substrate that can be usedin conjunction with the methods according to various embodimentsdisclosed herein include, but are not limited to, spin coating, spraycoating, spray and spin coating, curtain coating, flow coating, dipcoating, injection molding, casting, roll coating, wire coating, andovermolding.

According to other embodiments, applying the photochromic-dichroiccompound and the anisotropic material to the substrate can compriseforming a coating of the anisotropic material on a mold, which may betreated with a release material. Thereafter, the anisotropic materialcan be at least partially ordered (as discussed in more detail below)and at least partially set. Thereafter, the substrate can be formed overthe coating (i.e., overmolding), for example, by casting the substrateforming material in the mold. The substrate forming material can then beat least partially set to form the substrate. Subsequently, thesubstrate and the coating of the anisotropic material can be releasedfrom the mold. Further, according to this embodiment, thephotochromic-dichroic compound can be applied to the mold with theanisotropic material, or it can be imbibed into the anisotropic materialafter the anisotropic material has been applied to the mold, after theanisotropic material has been at least partially ordered, or after thesubstrate with the coating of the ordered anisotropic material has beenreleased from the mold.

According to other embodiments disclosed herein, forming the coatingcomprising the photochromic-dichroic compound can comprise applying ananisotropic material to the substrate, imbibing a photochromic-dichroiccompound into the anisotropic material, at least partially ordering theanisotropic material, and at least partially aligning thephotochromic-dichroic compound with the anisotropic material. Methods ofimbibing photochromic-dichroic compounds into various coatings aredescribed herein below in more detail.

Methods of ordering the anisotropic material include exposing theanisotropic material to at least one of a magnetic field, an electricfield, linearly polarized ultraviolet radiation, linearly polarizedinfrared radiation, linearly polarized visible radiation, and a shearforce. Further, the anisotropic material can be at least partiallyordered by aligning the anisotropic material with another material orstructure. For example, although not limiting herein, the anisotropicmaterial can be at least partially ordered by aligning the anisotropicmaterial with an orientation facility- such as, but not limited to,those orientation facilities previously discussed.

As previously described, by ordering at least a portion of theanisotropic material, it is possible to at least partially thephotochromic-dichroic compound that contained within or otherwiseconnected to the anisotropic material. Although not required, thephotochromic-dichroic compound can be at least partially aligned whilein an activated state. Further, according to various embodimentsdisclosed herein, applying the photochromic-dichroic compound and theanisotropic material to the substrate can occur at essentially the sametime as, prior to, or after ordering the anisotropic material and/oraligning the photochromic-dichroic compound.

For example, according to one embodiment, applying thephotochromic-dichroic compound and the anisotropic material can occur atessentially the same time as ordering the anisotropic material andaligning the photochromic-dichroic compound. More particularly,according to this limiting embodiment, the photochromic-dichroiccompound and anisotropic material can be applied to the substrate usinga coating technique that can introduce a shear force to the anisotropicmaterial during application such that the anisotropic material can be atleast partially ordered generally parallel to the direction of theapplied shear force. For example, although not limiting herein, asolution or mixture (optionally in a solvent or carrier) of thephotochromic-dichroic compound and the anisotropic material can becurtain coated on to the substrate such that shear forces are introducedto the materials being applied due to relative movement of the surfaceof the substrate with respect to the materials being applied. The shearforces can cause the anisotropic material to be ordered in a generaldirection that is essentially parallel to the direction of the movementof the surface. As discussed above, by ordering at least a portion ofthe anisotropic material in this manner, the photochromic-dichroiccompound which is contained within or connected to the anisotropicmaterial can be aligned by the anisotropic material. Further, althoughnot required, by exposing the photochromic-dichroic compound to actinicradiation during the curtain coating process, such that thephotochromic-dichroic compound is in an activated state, at leastpartial alignment of the photochromic-dichroic compound while in theactivated state can be achieved.

In another embodiment wherein the photochromic-dichroic compound and theanisotropic material are applied to the substrate prior to ordering theanisotropic material and aligning the photochromic-dichroic compound,applying the materials can comprise spin coating a solution or mixtureof the photochromic-dichroic compound and anisotropic material(optionally in a solvent or carrier) onto the substrate. Thereafter,according to this embodiment, the anisotropic material can be at leastpartially ordered, for example, by exposing the anisotropic material toa magnetic field, an electric field, linearly polarized ultravioletradiation, linearly polarized infrared radiation, linearly polarizedvisible radiation, or a shear force. Further the anisotropic materialcan be at least partially ordered by aligning the anisotropic materialwith another material or structure, for example, an orientationfacility.

In still another embodiment, wherein the photochromic-dichroic compoundis at least partially aligned and the anisotropic material is at leastpartially ordered prior to being applied to the substrate, a solution ormixture (optionally in a solvent or carrier) of thephotochromic-dichroic compound and the anisotropic material can beapplied to an ordered polymeric sheet to form a coating. Thereafter, theanisotropic material can be allowed to align with the polymeric sheet.The polymeric sheet can be subsequently applied to the substrate by, forexample, but not limited to, laminating or bonding. Alternatively, thecoating can be transferred from the polymeric sheet to the substrate bymethods known in the art, such as, but not limited to hot stamping.Other methods of applying polymeric sheets are described herein in moredetail.

In another embodiment, applying the photochromic-dichroic compound andanisotropic material to the substrate can comprise applying aphase-separating polymer system comprising a matrix phase-formingmaterial comprising a liquid crystal material and a guest phase-formingmaterial comprising the anisotropic material and photochromic-dichroiccompound. After applying the phase-separating polymer system, accordingto this embodiment, the liquid crystal material of the matrix phase andthe anisotropic material of the guest phase are at least partiallyordered, such that the photochromic-dichroic compound is aligned withthe anisotropic material of the guest phase. Methods of at leastpartially ordering the matrix phase-forming material and the guestphase-forming material of the phase-separating polymer system includeexposing the coating comprising the phase-separating polymer system toat least one of: a magnetic field, an electric field, linearly polarizedinfrared radiation, linearly polarized ultraviolet radiation, linearlypolarized visible radiation, and a shear force. Further, at leastpartially ordering the matrix phase-forming material and the guestphase-forming material can comprise at least partially aligning at theportions with an orientation facility, as described in more detailbelow.

After at least partially ordering the matrix phase-forming material andthe guest phase-forming material, the guest phase-forming material canbe separated from the matrix phase-forming material by polymerizationinduced phase separation and/or solvent induced phase separation.Although for clarity the separation of the matrix and guestphase-forming materials is described herein in relation to the guestphase-forming material separating from the matrix phase-formingmaterial, it should be appreciated that this language is intended tocover any separation between the two phase-forming materials. That is,this language is intended to cover separation of the guest phase-formingmaterial from the matrix phase-forming material and separation of thematrix phase-forming material from the guest phase-forming material, aswell as, simultaneous separation of both phase-forming materials and anycombination thereof.

According to various embodiments disclosed herein, the matrixphase-forming material can comprise a liquid crystal material chosenfrom liquid crystal monomers, liquid crystal pre-polymers, and liquidcrystal polymers. Further, according to various embodiments, the guestphase-forming material can comprise a liquid crystal material chosenfrom liquid crystal mesogens, liquid crystal monomers, and liquidcrystal polymers and pre-polymers. Examples of such materials are setforth in detail above.

In one specific embodiment, the phase-separating polymer system cancomprise a mixture of a matrix phase-forming material comprising aliquid crystal monomer, a guest phase-forming material comprising liquidcrystal mesogens, and at least one photochromic-dichroic compound.According to this embodiment, causing at least a portion of the guestphase-forming material to separate from at least a portion of the matrixphase-forming material can comprise polymerization inducedphase-separation. That is, at least a portion of the liquid crystalmonomer of the matrix phase can be polymerized and thereby separatedfrom the liquid crystal mesogens of the guest phase-forming material.Methods of polymerization that can be used in conjunction with variousembodiments disclosed herein include photo-induced polymerization andthermally-induced polymerization.

In another specific embodiment, the phase-separating polymer system cancomprise a mixture of a matrix phase-forming material comprising aliquid crystal monomer, a guest phase-forming material comprising a lowviscosity liquid crystal monomer having a different functionality fromthe liquid crystal monomer of the matrix phase, and at least onephotochromic-dichroic compound. As used herein, the term “low viscosityliquid crystal monomer,” refers to a liquid crystal monomer mixture orsolution that is freely flowing at room temperature. According to thisembodiment, causing at least a portion of the guest phase-formingmaterial to separate from at least a portion of the matrix phase-formingmaterial can comprise polymerization induced phase-separation. That is,at least a portion of the liquid crystal monomer of the matrix phase canbe polymerized under conditions that do not cause the liquid crystalmonomer of the guest phase to polymerize. During polymerization of thematrix phase-forming material, the guest phase-forming material willseparate from the matrix phase-forming material. Thereafter, the liquidcrystal monomer of the guest phase-forming material can be polymerizedin a separate polymerization process.

In another specific embodiment, the phase-separating polymer system cancomprise a solution in at least one common solvent of a matrixphase-forming material comprising a liquid crystal polymer, a guestphase-forming material comprising a liquid crystal polymer that isdifferent from the liquid crystal polymer of the matrix phase-formingmaterial, and a photochromic-dichroic compound. According to thisembodiment, causing at least a portion of the guest phase-formingmaterial to separate from the matrix phase-forming material can comprisesolvent induced phase-separation. That is, the common solvent can beevaporated from the mixture of liquid crystal polymers, thereby causingthe two phases to separate from each other.

Alternatively, according to various embodiments disclosed herein,forming the coating comprising the photochromic-dichroic compound cancomprise applying an anisotropic material to the substrate, imbibing thephotochromic-dichroic compound into the anisotropic material, at leastpartially ordering the anisotropic material, and at least partiallyaligning the photochromic-dichroic compound with the anisotropicmaterial. Further, although not limiting herein, at least partiallyordering the anisotropic material can occur before imbibing thephotochromic-dichroic compound thereinto. Still further, although notrequired, the photochromic-dichroic compound can be at least partiallyaligned while in an activated state. Methods of applying and aligninganisotropic materials are described herein below.

For example, according to one embodiment, the photochromic-dichroiccompound can be imbibed into the anisotropic material, for example, byapplying a solution or mixture of the photochromic-dichroic compound ina carrier to a portion of the anisotropic material and allowing thephotochromic-dichroic compound to diffuse into the anisotropic material,either with or without heating. Further, according to this embodiment,the anisotropic material can be part of a phase-separated polymercoating as described above.

Other embodiments disclosed herein provide a method of making an opticalelement comprising imparting at least one orientation facility to asubstrate, and subsequently forming a coating comprising an at leastpartially aligned photochromic-dichroic compound on the orientationfacility. According to this and other embodiments disclosed herein,imparting the orientation facility to the substrate can comprise atleast one of: forming a coating comprising an at least partially orderedalignment medium on the substrate, applying an at least partiallyordered polymer sheet to the substrate, treating the substrate, andforming a Langmuir-Blodgett film on the substrate.

According to one embodiment, imparting the orientation facility on thesubstrate can comprise forming a coating comprising an at leastpartially ordered alignment medium on the substrate. Further, accordingto this embodiment, forming the coating can comprise applying analignment medium to the substrate and at least partially ordering thealignment medium. Methods of ordering the alignment medium that can beused in conjunction with this and other embodiments disclosed hereininclude, but are not limited to, exposing the alignment medium to atleast one of linearly polarized ultraviolet radiation, linearlypolarized infrared radiation, linearly polarized visible radiation, amagnetic field, an electric field, and a shear force. Further, orderingthe alignment medium can comprise treating the coating comprising thealignment medium by, for example and without limitation, etching orrubbing the at least a portion of the alignment medium.

For example, although not limiting herein, according to one embodimentwherein the orientation facility comprises a coating comprising analignment medium that is a photo-orientation material (such as, but notlimited to a photo-orientable polymer network), imparting theorientation facility can comprise forming a coating comprising aphoto-orientation material on the substrate, and at least partiallyordering the photo-orientation material by exposing the material tolinearly polarized ultraviolet radiation. Thereafter, thephotochromic-dichroic compound can be applied to the photo-orientationmaterial and at least partially aligned.

Although not required, according to various embodiments whereinimparting the orientation facility comprises forming a coating of an atleast partially ordered alignment medium, the alignment medium can be atleast partially set. Further, setting the alignment medium can occur atessentially the same time as aligning the alignment medium or it canoccur after aligning the alignment medium. Still further, according tovarious embodiments disclosed herein, setting the alignment medium cancomprise at least partially curing the medium by exposing it toinfrared, ultraviolet, gamma, microwave or electron radiation so as toinitiate the polymerization reaction of the polymerizable components orcross-linking with or without a catalyst or initiator. If desired orrequired, this can be followed by a heating step.

As discussed above, according to various embodiments disclosed herein,subsequent to imparting the orientation facility on the substrate, acoating comprising an at least partially aligned photochromic-dichroiccompound is formed on the orientation facility. Methods of forming suchcoatings include those methods of forming coatings comprising aphotochromic-dichroic compound that is at least partially aligned on asubstrate that are set forth above in detail.

For example, although not limiting herein, forming the coatingcomprising the photochromic-dichroic compound can include, spin coating,spray coating, spray and spin coating, curtain coating, flow coating,dip coating, injection molding, casting, roll coating, wire coating, andovermolding a composition comprising the photochromic-dichroic compoundon to the orientation facility, and thereafter, aligning thephotochromic-dichroic compound with the orientation facility and/or withanother material or structure (such as an alignment transfer material ifpresent), with or without exposure to a magnetic field, an electricfield, linearly polarized infrared radiation, linearly polarizedultraviolet radiation, linearly polarized visible radiation or a shearforce.

According to one embodiment, forming the coating comprising thephotochromic-dichroic compound that is at least partially aligned on theorientation facility can comprise applying a polymerizable composition,an anisotropic material, and a photochromic-dichroic compound on theorientation facility. Thereafter, the anisotropic material can be atleast partially aligned with the orientation facility and thephotochromic-dichroic compound with the anisotropic material. Afteraligning the anisotropic material and the photochromic-dichroiccompound, the coating can be subjected to a dual curing process, whereinthe anisotropic material and the polymerizable composition are at leastpartially set using at least two curing methods. Examples of suitablecuring methods include exposing the coating to ultraviolet radiation,visible radiation, gamma radiation, microwave radiation, electronradiation, or thermal energy.

For example, although not limiting herein, in one embodiment theanisotropic material can be exposed to ultraviolet or visible radiationto cause the anisotropic material to at least partially set. Thereafter,the polymerizable composition can be at least partially set by exposureto thermal energy. Further, although not required thephotochromic-dichroic compound can be at least partially aligned withthe anisotropic material while in an activated state by exposing thecoating to ultraviolet radiation sufficient to cause thephotochromic-dichroic compound to switch from a first state to a secondstate, but insufficient to cause the anisotropic material to set, whilethe anisotropic material is at least partially aligned with theorientation facility (as discussed above).

In one specific embodiment, the polymerizable composition can bedihydroxy and isocyanate monomers and the anisotropic material cancomprise a liquid crystal monomer. According to this embodiment, afterapplying the polymerizable composition, the anisotropic material and thephotochromic-dichroic compound on the orientation facility, theanisotropic material can be at least partially aligned with theorientation facility and the photochromic-dichroic compound can be atleast partially aligned with the anisotropic material. Further, afteralignment, the coating can be exposed to ultraviolet or visibleradiation sufficient to cause the anisotropic material to leastpartially set. Further, before, during or after setting the anisotropicmaterial, the polymerizable composition can be at least partially set byexposing the coating to thermal energy.

In another embodiment, the dual cure process can comprise first exposingthe polymerizable composition to thermal energy sufficient to cause thepolymerizable composition to at least partially set. Thereafter, theanisotropic material can be exposed to ultraviolet or visible radiationto cause the anisotropic material to at least partially set. Further,the anisotropic material can be at least partially aligned before,during or after exposing the coating to thermal energy and prior tosetting the anisotropic material.

In still another embodiment, the dual cure process can comprise settingthe polymerizable composition at essentially the same time as settingthe anisotropic material, for example, by simultaneously exposing thecoating to ultraviolet or visible radiation and thermal energy.

Further, as previously discussed in relation to coatings comprisinginterpenetrating polymer networks, according to various embodimentsdisclosed herein, the polymerizable composition can be an isotropicmaterial or an anisotropic material, provided that the coatingcomprising the photochromic-dichroic compound is, on the whole,anisotropic.

Additionally, the methods of making optical elements and devicesaccording to various embodiments disclosed herein can further compriseforming a primer coating on the substrate prior to imparting theorientation facility to the substrate or prior to forming a coatingcomprising the photochromic-dichroic compound thereon. Moreover, atleast one additional coating chosen from photochromic coatings,anti-reflective coatings, linearly polarizing coatings, circularlypolarizing coatings, elliptically polarizing coatings, transitionalcoatings, primer coatings and protective coatings can be formed on thesubstrate and/or over the coating comprising the photochromic-dichroiccompound. Examples of suitable primer coatings, photochromic coatings,anti-reflective coatings, linearly polarizing coatings, transitionalcoatings, primer coatings and protective coatings are all describedabove.

Other embodiments disclosed herein provide methods of making an opticalelement comprising forming a coating on a substrate and adapting thecoating to switch from a first state to a second linearly polarizingstate in response to actinic radiation and to revert back to the firststate in response to thermal energy. According to one embodiment formingthe coating on the substrate and adapting the coating to switch from afirst state to a second linearly polarizing state in response to actinicradiation and to revert back to the first state in response to thermalenergy can occur at essentially the same time. According to anotherembodiment, forming the coating on the substrate occurs prior toadapting the coating to switch from a first state to a second linearlypolarizing state in response to actinic radiation and to revert back tothe first state in response to thermal energy. According to stillanother embodiment, forming the coating on the substrate occurs afteradapting the coating to switch from a first state to a second linearlypolarizing state in response to actinic radiation and to revert back tothe first state in response to thermal energy.

In one embodiment, forming the coating on the substrate can compriseapplying an anisotropic material and a photochromic-dichroic compound tothe substrate, and adapting the coating to switch from a first state toa second linearly polarizing state in response to actinic radiation andto revert back to the first state in response to thermal energy cancomprise at least partially aligning the photochromic-dichroic compound.Further, according to this embodiment at least partially aligning thephotochromic-dichroic compound can comprise at least partially orderingthe anisotropic material and at least partially aligning thephotochromic-dichroic compound with the anisotropic material. Stillfurther, although not required, the photochromic-dichroic compound canbe aligned while in an activated state, for example, by exposing thephotochromic-dichroic compound to actinic radiation sufficient to causethe photochromic-dichroic compound to switch from a first state to asecond state while aligning the photochromic-dichroic compound.

In another embodiment, forming the coating on the substrate can compriseapplying an alignment medium to the substrate, and adapting the coatingto switch from a first state to a second linearly polarizing state inresponse to actinic radiation and to revert back to the first state inresponse to thermal energy can comprise at least partially ordering thealignment medium, applying a photochromic-dichroic compound to thecoating comprising the alignment medium, and at least partially aligningthe photochromic-dichroic compound.

In one embodiment, applying the photochromic-dichroic compound to thecoating comprising the alignment medium can comprise forming a coatingcomprising the photochromic-dichroic compound and an anisotropicmaterial on the coating comprising the alignment medium. Moreover, atleast partially aligning the photochromic-dichroic compound can comprisealigning the anisotropic material with the alignment medium. Further,although not required, the coating comprising the alignment medium canbe at least partially set prior to applying the photochromic-dichroiccompound.

Additionally or alternatively, the photochromic-dichroic compound can beapplied to the coating comprising the at least partially orderedalignment medium by imbibition. Suitable imbibition techniques aredescribed, for example, U.S. Pat. Nos. 5,130,353 and 5,185,390, thespecifications of which are specifically incorporated by referenceherein. For example, although not limiting herein, thephotochromic-dichroic compound can be applied to the coating comprisingthe at least partially ordered alignment medium by applying thephotochromic-dichroic compound, either as the neat photochromic-dichroiccompound or dissolved in a polymeric or other organic solvent carrier,and allowing the photochromic-dichroic compound to diffuse into thecoating comprising the at least partially ordered alignment medium,either with or without heating. Further, if desired, thephotochromic-dichroic compound can be exposed to actinic radiationsufficient to cause the photochromic compound to switch from a firststate to a second state during diffusion.

Other embodiments disclosed herein provide a method of making an opticalelement comprising forming a coating comprising an alignment medium on asubstrate and at least partially ordering the alignment medium, forminga coating comprising an alignment transfer material on the coatingcomprising the alignment medium and at least partially aligning thealignment transfer material with the alignment medium, and forming acoating comprising an anisotropic material and a photochromic-dichroiccompound on the alignment transfer material, at least partially aligningthe anisotropic material with the alignment transfer material, and atleast partially aligning the photochromic-dichroic compound with theanisotropic material.

Further, according to various embodiments disclosed herein, forming thecoating comprising the alignment transfer material can comprise forminga first coating comprising an alignment transfer material, the firstcoating having a thickness ranging from 2 to 8 microns, at leastpartially aligning the alignment transfer material of the first coatingwith the alignment medium, and setting the alignment transfer materialof the first coating. Thereafter, a second coating having a thicknessranging from greater than 5 to 20 microns and comprising an alignmenttransfer material can be applied to the first coating and the alignmenttransfer material of the second coating can be at least partiallyaligned with the alignment transfer material of the first coating.

Still other embodiments disclosed herein provide a method of making acomposite optical element comprising connecting at least one at leastpartially ordered polymeric sheet to at least a portion of a substrate,the at least partially ordered polymeric sheet comprising at least oneat least partially aligned photochromic-dichroic compound connected toat least a portion thereof and having an average absorption ratiogreater than 2.3 in an activated state as determined according to theCELL METHOD. Although not limiting herein, according to this embodiment,the at least one at least partially ordered polymeric sheet cancomprise, for example, a stretched polymer sheet, a photo-orientedpolymer sheet, an at least partially ordered phase-separated polymersheet, or a combination thereof.

[01] Other embodiments disclosed herein provide a method of making acomposite optical element comprising connecting a sheet comprising an atleast partially ordered liquid crystal polymer having a first generaldirection, an at least partially ordered liquid crystal materialdistributed within the liquid crystal polymer, and aphotochromic-dichroic compound that is at least partially aligned withthe liquid crystal material to the substrate. Further, according to thisembodiment, the liquid crystal material distributed within the liquidcrystal polymer can have a second general direction that is generallyparallel to the liquid crystal polymer.

For example, although not limiting herein, according to one embodiment,forming the sheet can comprise applying a phase-separating polymersystem comprising a matrix phase-forming material comprising a liquidcrystal material, a guest phase-forming material comprising a liquidcrystal material, and at least one photochromic-dichroic compound on toa substrate. Thereafter, the matrix phase-forming material and the guestphase-forming material can be at least partially ordered, and thephotochromic-dichroic compound can be at least partially aligned withthe guest phase-forming material. After alignment, the guestphase-forming material can be separated from the matrix phase-formingmaterial by polymerization induced phase-separation and/or solventinduced phase-separation, and the phase-separated polymer coating can beremoved from the substrate to form the sheet.

Alternatively, the phase-separating polymer system can be applied on thesubstrate, ordered and aligned as discussed above, and thereafterremoved from the substrate to form a phase-separated polymer sheet.Subsequently, a photochromic-dichroic compound can be imbibed into thesheet. Alternatively or additionally, a photochromic-dichroic compoundcan be imbibed into the coating prior to removing the coating from thesubstrate to form the sheet.

According to still another embodiment forming the sheet can comprise:forming an at least partially ordered liquid crystal polymer sheet andimbibing liquid crystal mesogens and a photochromic-dichroic compoundinto the liquid crystal polymer sheet. For example, according to thisembodiment, a sheet comprising a liquid crystal polymer can be formedand at least partially ordered by a method of forming a polymer sheetthat can at least partially order the liquid crystal polymer duringformation, for example by extrusion. Alternatively, a liquid crystalpolymer can be cast onto a substrate and at least partially ordered byone of the methods of ordering liquid crystal materials set forth above.For example, although not limiting herein, the liquid crystal materialcan be exposed to a magnetic or an electric field. After being at leastpartially ordered, the liquid crystal polymer can be at least partiallyset and removed from the substrate to form a sheet comprising an atleast partially ordered liquid crystal polymer matrix. Still further, aliquid crystal polymer sheet can be cast, at least partially set, andsubsequently stretched to form sheet comprising an at least partiallyordered liquid crystal polymer.

After forming the sheet comprising the at least partially ordered liquidcrystal polymer, a liquid crystal mesogen and a photochromic-dichroiccompound can be imbibed into the liquid crystal polymer matrix. Forexample, although not limiting herein, the liquid crystal mesogen andthe photochromic-dichroic compound can be imbibed into the liquidcrystal polymer by applying a solution or mixture of the liquid crystalmesogen and the photochromic-dichroic compound in a carrier to theliquid crystal polymer and, thereafter, allowing the liquid crystalmesogen and the photochromic-dichroic compound to diffuse into theliquid crystal polymer sheet, either with or without heating.Alternatively, the sheet comprising the liquid crystal polymer can beimmersed into a solution or mixture of the liquid crystal mesogen andthe photochromic-dichroic compound in a carrier and the liquid crystalmesogen and the photochromic-dichroic compound can be imbibed into theliquid crystal polymer sheet by diffusion, either with or withoutheating.

According to still another embodiment, forming the sheet can compriseforming a liquid crystal polymer sheet, imbibing the liquid crystalpolymer sheet with a liquid crystal mesogen and a photochromic-dichroiccompound (for example as discussed above), and thereafter at leastpartially ordering the liquid crystal polymer, the liquid crystalmesogen, and the photochromic-dichroic compound distributed therein.Although not limiting herein, for example, the liquid crystal polymersheet, the liquid crystal mesogen, and the photochromic-dichroiccompound distributed therein can be at least partially ordered bystretching the liquid crystal polymer sheet. Further according to thisembodiment, the liquid crystal polymer sheet can be formed usingconventional polymer processing techniques, such as, but not limited to,extrusion and casting.

In still another embodiment, a photo-oriented polymer sheet comprising acoating of an anisotropic material and a photochromic-dichroic compoundis applied to the substrate. For example, according to this embodiment,photo-oriented polymer sheet can be formed by applying a layer of aphoto-orientable polymer network on a release layer and subsequentlyordering and at least partially curing the photo-orientable polymernetwork; forming a coating of an anisotropic material and aphotochromic-dichroic compound on the layer comprising thephoto-orientable polymer network, at least partially aligning theanisotropic material and the photochromic-dichroic compound with thephoto-orientable polymer network, and curing the anisotropic material.The release layer can then be removed and the layer of thephoto-orientable polymer network comprising the coating of theanisotropic material and the photochromic-dichroic compound from therelease layer to form the ordered polymeric sheet.

Further, according to various embodiments disclosed herein, connectingthe polymeric sheet comprising the photochromic-dichroic compound to thesubstrate can comprise, for example, at least one of: laminating,fusing, in-mold casting, and adhesively bonding the polymeric sheet tothe substrate. As used herein, the in-mold casting includes a variety ofcasting techniques, such as but not limited to: overmolding, wherein thesheet is placed in a mold and the substrate is formed (for example bycasting) over at least a portion of the sheet; and injection molding,wherein the substrate is formed around the sheet. According to oneembodiment, the polymeric sheet can be laminated on a surface of a firstportion of the substrate, and the first portion of the substrate can beplaced in a mold. Thereafter, a second portion of the substrate can beformed (for example by casting) on top of the first portion of thesubstrate such that the polymeric layer is between the two portions ofthe substrate.

Another specific embodiment provides a method of making an opticalelement comprising overmolding a coating comprising an at leastpartially ordered liquid crystal material and an at least partiallyaligned photochromic-dichroic compound on an optical substrate, and moreparticularly, on an ophthalmic substrate. Referring now to FIG. 2,according to this embodiment, the method comprises placing a surface 210of an optical substrate 212 adjacent a to a surface 214 of a transparentmold 216 to define a molding region 217. The surface 214 of transparentmold 216 can be concave or spherically negative (as shown), or it canhave other configurations as required. Further, although not required, agasket or spacer 215 can be placed between optical substrate 212 andtransparent mold 216. After positioning the optical substrate 212, aliquid crystal material 218 containing at least onephotochromic-dichroic compound (not shown) can be introduced into themolding region 217 defined by the surface 210 of the optical substrate212 and the surface 214 of the transparent mold 216, such that at leasta portion of the liquid crystal material 218 is caused to flowtherebetween. Thereafter, the liquid crystal material 218 can be atleast partially ordered, for example, by exposure to an electric field,a magnetic field, linearly polarized infrared radiation, linearlypolarized ultraviolet radiation, and/or linearly polarized visibleradiation, and the photochromic-dichroic compound can be at leastpartially aligned with the liquid crystal material. Thereafter, theliquid crystal material can be polymerized. After polymerization, theoptical substrate having the coating comprising an at least partiallyordered liquid crystal material and the photochromic-dichroic compoundon a surface thereof can be released from the mold.

Alternatively, the liquid crystal material 218 containing thephotochromic-dichroic compound can be introduced onto surface 214 oftransparent mold 216 prior to placing at least a portion of surface 210of the optical substrate 212 adjacent thereto such that at least aportion of surface 210 contacts at least a portion of the liquid crystalmaterial 218, thereby causing the liquid crystal material 218 to flowbetween surface 210 and surface 214. Thereafter, the liquid crystalmaterial 218 can be at least partially ordered, and thephotochromic-dichroic compound can be at least partially aligned asdiscussed above. After polymerization of the liquid crystal material,the optical substrate having the coating comprising an at leastpartially ordered liquid crystal material and the photochromic-dichroiccompound on a surface thereof can be released from the mold.

According to still other embodiments, a coating comprising at leastpartially ordered liquid crystal material, without thephotochromic-dichroic compound, can be formed on the surface of anoptical substrate as discussed above. After releasing the substrate andthe coating from the mold, a photochromic-dichroic compound can beimbibed into the liquid crystal material.

Although not shown in FIG. 2, additionally or alternatively, anorientation facility having a first general direction can be impartedonto the surface of the transparent mold prior to introducing the liquidcrystal material into the mold and/or onto the surface of the opticalsubstrate prior contacting the surface of the optical substrate with theliquid crystal material. Further, according to this embodiment, orderingthe liquid crystal material can comprise at least partially aligning theliquid crystal material with the orientation facility on the surface ofthe mold and/or on the surface of the optical substrate.

After preparation of the photochromic linear polarizing element usingany of the methods disclosed above, the birefringent layer (b) isconnected thereto. The birefringent layer can be applied to thephotochromic linear polarizing element by, for example, laminating oradhesive bonding. Alternatively, the birefringent layer (b) can beconnected to the photochromic linear polarizing element by methods knownin the art, such as hot stamping. Suitable adhesives for connecting thebirefringent layer to the photochromic linear polarizing element includethose disclosed in U.S. Pat. No. 6,864,932 at column 4, line 65 throughcolumn 60, incorporated herein by reference.

Although not limiting herein, it is contemplated that the aforementionedover molding methods of making coatings can be particularly useful informing coatings on multi-focal ophthalmic lenses, or for formingcoatings for other applications where relatively thick alignmentfacilities are desired.

As previously discussed, various embodiments disclosed herein relate todisplay elements and devices. Further, as previously discussed, as usedherein the term “display” means the visible representation ofinformation in words, numbers, symbols, designs or drawings. Examples ofdisplay elements and devices include screens, monitors, and securityelements. Examples of security elements include security marks andauthentication marks that are connected to a substrate, such as andwithout limitation: access cards and passes, e.g., tickets, badges,identification or membership cards, debit cards etc.; negotiableinstruments and non-negotiable instruments, e.g., drafts, checks, bonds,notes, certificates of deposit, stock certificates, etc.; governmentdocuments, e.g., currency, licenses, identification cards, benefitcards, visas, passports, official certificates, deeds etc.; consumergoods, e.g., software, compact discs (“CDs”), digital-video discs(“DVDs”), appliances, consumer electronics, sporting goods, cars, etc.;credit cards; and merchandise tags, labels and packaging.

For example, in one embodiment, the display element is a securityelement connected to a substrate. According to this embodiment thesecurity element comprises a coating having a first state and a secondstate, and being adapted to switch from a first state to a second statein response to at least actinic radiation, to revert back to the firststate in response to thermal energy, and to linearly polarizetransmitted radiation in at least one of the first state and the secondstate. Examples of coatings adapted to switch from a first state to asecond state in response to at least actinic radiation, to revert backto the first state in response to thermal energy, and to linearlypolarize at least transmitted radiation in at least one of the firststate and the second state and methods of making the same are set forthabove in detail.

According to this embodiment, the security element can be a securitymark and/or an authentication mark. Further, the security element can beconnected to a substrate chosen from a transparent substrate and areflective substrate. Alternatively, according to certain embodimentswherein a reflective substrate is required, if the substrate is notreflective or sufficiently reflective for the intended application, areflective material can be first applied to the substrate before thesecurity mark is applied thereto. For example, a reflective aluminumcoating can be applied to the substrate prior to forming the securityelement thereon. Still further, the security element can be connected toa substrate chosen from untinted substrates, tinted substrates,photochromic substrates, tinted-photochromic substrates, linearlypolarizing substrates, circularly polarizing substrates, andelliptically polarizing substrates.

Additionally, the coatings according to the aforementioned embodimentcan comprise at least one photochromic-dichroic compound having anaverage absorption ratio of at least 1.5 in an activated state asdetermined according to the CELL METHOD. According to other embodimentsdisclosed herein, the photochromic-dichroic compound can have an averageabsorption ratio greater than 2.3 in an activated state as determinedaccording to the CELL METHOD. According to still other embodiments, thephotochromic-dichroic compound can have an average absorption ratioranging from 1.5 to 50 in an activated state as determined according tothe CELL METHOD. According to other embodiments, thephotochromic-dichroic compound can have an average absorption ratioranging from 4 to 20, can further having an average absorption ratioranging from 3 to 30, and can still further having an average absorptionratio ranging from 2.5 to 50 in an activated state as determinedaccording to the CELL METHOD. However, generally speaking, the averageabsorption ratio of the photochromic-dichroic compound can be anyaverage absorption ratio that is sufficient to impart the desiredproperties to the device or element. Examples of photochromic-dichroiccompounds that are suitable for use in conjunction with this embodimentare set forth above in detail.

Furthermore, the security elements according to the aforementionedembodiment can further comprise one or more other coatings or sheets toform a multi-layer reflective security element with viewing angledependent characteristics as described in U.S. Pat. No. 6,641,874, whichis hereby specifically incorporated by reference herein. For example,one embodiment provides a security element connected to a substratecomprising a coating having a first state and a second state, and beingadapted to switch from a first state to a second state in response to atleast actinic radiation, to revert back to the first state in responseto thermal energy, and to linearly polarize at least transmittedradiation in at least one of the first state and the second state on atleast a portion of the substrate; and at least one additional at leastpartial coating or sheet chosen from a birefringent layer, polarizingcoatings or sheets, photochromic coatings or sheets, reflective coatingsor sheets, tinted coatings or sheets, circularly polarizing coatings orsheets, retardation coatings or sheets (i.e., coatings or sheets thatdelay or retard the propagation radiation therethrough), and wide-angleview coatings or sheets (i.e., coatings or sheets than enhancing viewingangle). Further, according to this embodiment, the at least oneadditional coating or sheet can be positioned over the coating havingthe first state and the second state, under this coating, or multiplecoating and/or sheets can be positioned over and/or under this coating.

Other embodiments provide a liquid crystal cell, which may be a displayelement or device, comprising a first substrate having a first surfaceand a second substrate having a second surface, wherein the secondsurface of the second substrate is opposite and spaced apart from thefirst surface of the first substrate so as to define an open region.Further, according to this embodiment, a liquid crystal material adaptedto be at least partially ordered and a photochromic-dichroic compoundadapted to be at least partially aligned and having an averageabsorption ratio of at least 1.5 in the activated state as determinedaccording to the CELL METHOD positioned within the open region definedby the first surface and the second surface to form the liquid crystalcell.

Further according to this embodiment, the first substrate and the secondsubstrate can be independently chosen from untinted substrates, tintedsubstrates, photochromic substrates, tinted-photochromic substrates, andlinearly polarizing substrates.

The liquid crystal cells according to various embodiments disclosedherein can further comprise a first orientation facility positionedadjacent the first surface and a second orientation facility positionedadjacent the second surface. As previously discussed, it is possible toalign a liquid crystal material with an oriented surface. Thus,according to this embodiment, the liquid crystal material of the liquidcrystal cell can be at least partially aligned with the first and secondorientation facilities.

Still further, a first electrode can be positioned adjacent the firstsurface, a second electrode can be positioned adjacent the secondsurface, and the liquid crystal cell can form an electrical circuit.Further, if an orientation facility is present (as discussed above), theelectrode can be interposed between the orientation facility and thesurface of the substrate.

Additionally, the liquid crystal cells according to various embodimentsdisclosed herein can further comprise a coating or sheet chosen fromlinearly polarizing coatings or sheets, photochromic coatings or sheets,reflective coatings or sheets, tinted coatings or sheets, circularlypolarizing coatings or sheets, elliptically polarizing coating orsheets, retardation coatings or sheets, and wide-angle view coatings orsheets connected to at least a portion of a surface of at least one ofthe first substrate and the second substrate.

Other embodiments disclosed herein provide an optical element comprisinga substrate and a coating having a first state and a second state on atleast a portion of the substrate, the coating comprising a chiralnematic or cholesteric liquid crystal material having molecules that arehelically arranged through the thickness of the coating; and at leastone photochromic-dichroic compound that is at least partially alignedwith the liquid crystal material such that the long axis of themolecules of the photochromic-dichroic compound are generally parallelto the molecules of the liquid crystal material. According to thisembodiment, the coating can be adapted to be circularly polarizing orelliptically polarizing in at least one state.

In another non-limiting embodiment, the optical element of the presentinvention comprises a substrate such as packaging material forlight-sensitive products to which a circular polarizer comprising anassembly of a linearly polarizing coating or an at least partiallyordered polymeric sheet comprising an at least partially alignedreversible photochromic-dichroic material having an average absorptionratio of at least 1.5 in an activated state and a quarter wave retarderis connected. In a further non-limiting embodiment, the averageabsorption ratio is at least 2.3.

Various embodiments disclosed herein will now be illustrated in thefollowing examples.

EXAMPLES Example 1 Step 1—Photochromic Dye Mixture

A mixture of the solid photochromic dyes (1.6 grams) listed below wasprepared by adding the dyes to a glass bottle and mixing with a spatula.

Photochromic Dye Weight Percent of Total Dye Mixture Photochromic A ⁽¹⁾28.0 Photochromic B ⁽²⁾ 17.8 Photochromic C ⁽³⁾ 22.2 Photochromic D ⁽⁴⁾32.0 ⁽¹⁾ Photochromic A is an indenonaphthopyran reported to produce alight purple activated color. ⁽²⁾ Photochromic B is anindenonaphthopyran reported to produce a peach activated color. ⁽³⁾Photochromic C is an indenonaphthopyran reported to produce a blue greenactivated color. ⁽⁴⁾ Photochromic D is an indenonaphthopyran reported toproduce a green blue activated color.

Step 2—Resin Stabilizer Mixture

A mixture of the solid stabilizers was prepared to deliver the weightpercent based on the weight of the total resin solids as listed in theTable below.

Stabililzer Weight Percent of Resin Solids TINUVIN ® 144 ⁽⁵⁾ 0.5IRGAPHOS ® 12 ⁽⁶⁾ 1.0 IRGANOX ® 1010 ⁽⁷⁾ 1.0 ⁽⁵⁾ TINUVIN ® 144 isreported to be a light stabilizer of the hindered amine class (HALS)having CAS No. 63843-89-0 available from CIBA Specialty Chemicals. ⁽⁶⁾IRGAFOS ® 12 is reported to be a polymer processing stabilizer havingCAS No. 80410-33-9 available from CIBA Specialty Chemicals. ⁽⁷⁾IRGANOX ® 1010 is reported to be a polymer processing and thermalstabilizer having CAS No. 6683-19-8.

Step 3—Polymer Processing

A Plasti-Corder mixer (made by C. W. Brabender Instruments, Inc.) washeated to 190° C. PEBAX® 5533 resin (about 40 grams), reported to be apolyether block amide available from Arkema, was added to the mixinghead and mixed at 65 to 80 revolutions per minute (rpm) until melted.The resin stabilizer mixture from Step 2 was added and mixed at the samespeed for about 1 minute. The photochromic dye mixture from Step 1 wasadded and mixed at the same speed for about 2 minutes. The resultingmixed material was removed from the Plasti-Corder mixer by reversing thedirection of the mixing heads.

The recovered photochromic resin was placed between two Teflon® coatedsteel plates positioned in a PHI temperature controlled press. The presswas heated to 190° C. After the photochromic resin began to melt on thebottom plate, the top plate was applied with increasing pressure for 1minute and then the pressure was increased to 2-3 tons for about 2minutes. After the pressure was released, the film coated plates wereremoved, allowed to cool at 20-25° C. for 4-5 minutes and immersed inwater at from 15-25° C. water for 1-2 minutes. The Pebax film separatedeasily from the Teflon coated steel plates.

Step 4—Sample Preparation Part A

A portion of the film from Step 3 was cut into a 5 by 5 centimeter (cm)piece that was placed between 2 MYLAR® polyester films with 100 micronaluminum spacers. The assembly was placed between two Teflon® coatedsteel plates positioned in a PHI temperature controlled press. The presswas heated to 190° C. After the steel plates were in contact with theassembly for 1 minute, the pressure was increased to 2-3 tons for 7 to10 minutes. After the pressure was released, the steel plates and theassembly were immersed in ice water to cool the sample from 190° C. to0° C. in less than 20 seconds. The photochromic resin films were pulledapart from the MYLAR® polyester films.

Part B

A portion of the film from Part A was cut into a 5 by 5 cm piece andplaced in the sample holders of an INSTRON® SF7 model 5543 instrument.The gap between the holders was 1 inch. The sample was stretched to 4×(101.5 mm) at a rate of 10 mm/minute under conditions of 20-22° C. and40-65% relative humidity. After stretching, the 1 inch film was shown tobe stretched roughly to 3.5 inches. Two films (Film 1 and Film 2) wereproduced following this procedure.

Part C

Film 1 was placed between 2 fused silica plates having a thickness of3.3 mm and diameter of 50.86 mm available from McMaster Car and theplates were taped together. Film 1 is a clear to linear polarizer. For aclear to circular polarizer, 1 fused silica plate was placed in a PS-100polarimeter. A ¼-wave plate obtained from Alight, having 140+/−10 nmretardation was added to the fused silica plate and oriented betweencrossed polarizers to get a null position indicating that the opticalaxes are along the same directions as the 2 linear polarizertransmission axes. Film 2 was added on top of the ¼-wave plate and wasoriented independently until a maximum light intensity was observed. Inthis position, the orientation of Film 2 was such that the filmstransmission axis was 45 degrees between the fast and slow optical axesof the ¼-wave plate. A second fused silica disk was place on top ofthese films and the whole stack was taped together. Alignment of Film 2to 45 degrees between the fast and slow axes of the ¼-wave plate wasestimated to be 45+/−3 degrees.

Visual inspection of the UV activated samples with a linear polarizerand a circular polarizer showed that the Film 1 was a clear to linearpolarizer and the stack of Film 2 with the ¼-wave plate demonstratedclear to circular polarization.

Step 5—Sample Testing

An optical bench was used to measure the optical properties of the filmsand derive the absorption ratios for each of the films when tested forclear to polarized and clear to circular polarized properties. Prior totesting, each of the samples was exposed to activating radiation (UVA)for 10 minutes at a distance of 15 centimeters (cm) from a bank of fourUV Tubes BLE-7900B supplied by Spectronics Corp and then placed for onehour at 40° C. Subsequently, the samples were exposed for one hour at adistance of 15 cm from a bank of four UVIess tubes F4OGO supplied byGeneral Electric and finally held in the dark for at one hour.Afterwards, the stretched film assemblies were placed in a temperaturecontrolled air cell at (23° C.±0.1° C.) on the optical bench. Theactivating light source (a Newport/Oriel Model 67005 300-Watt Xenon arclamp housing, 69911 power supply and 68945 digital exposure controllerfitted with a Uniblitz VS25 (with VMM-D4 shutter driver) high-speedcomputer controlled shutter that momentarily closed during datacollection so that stray light would not interfere with the datacollection process, a Schott 3 mm KG-2 band-pass filter, which removedshort wavelength radiation, neutral density filter(s) for intensityattenuation and a condensing lens for beam collimation) was directed ata 30° to 35° angle of incidence to the surface of the stretched filmside and not the ¼ wave plate side of the cell assembly.

A broadband light source for monitoring response measurements waspositioned in a perpendicular manner to a surface of the cell assembly.Increased signal of shorter visible wavelengths was obtained bycollecting and combining separately filtered light from a 100-Watttungsten halogen lamp (controlled by a Lambda UP60-14 constant voltagepowder supply) with a split-end, bifurcated fiber optical cable. Lightfrom one side of the tungsten halogen lamp was filtered with a SchottKG1 filter to absorb heat and a Hoya B-440 filter to allow passage ofthe shorter wavelengths. The other side of the light was either filteredwith a Schott KG1 filter or unfiltered. The light was collected byfocusing light from each side of the lamp onto a separate end of thesplit-end, bifurcated fiber optic cable, and subsequently combined intoone light source emerging from the single end of the cable. A 4″ lightpipe was attached to the single end of the cable to insure propermixing.

Polarization of the light source was achieved by passing the light fromthe single end of the cable through a Moxtek, Proflux Polarizer held ina computer driven, motorized rotation stage (Model M-061-PD fromPolytech, PI). The monitoring beam was set so that the one polarizationplane (0°) was perpendicular to the plane of the optical bench table andthe second polarization plane (90°) was parallel to the plane of theoptical bench table.

Alignment of the polarization samples was accomplished by aligning thesamples to find the null intensity between crossed polarizers. Prior toUV activation Films 1 and 2 were aligned as follows. Electrical dark,reference and dark spectra were collected at both 0 and 90 degreepolarization directions. Film 1 was placed in the beam path and thelaser (Coherent Ultra-low noise diode laser module centered at 635 nm)was directed through the crossed polarizers and sample by translatingbeam steering mirrors and a second MG polarizer (crossed with the Moxtekpolarizer) into the beam path. The sample was rotated in 3 degree stepsthrough 120 degrees to find a minimum in the counts. Then the sample wasrotated +/−5 degrees around this minimum at 0.1 degree steps to locatethe alignment direction of the sample to +/−0.1 degrees. The sample wasnow aligned to be either vertical or horizontal. The laser was switchedclosed, the laser directing mirrors and MG polarizer were removed fromthe optical path.

To conduct the clear to linear measurements, the cell assembly wasexposed to 6.7 W/m² of UVA from the activating light source for 15minutes to activate the photochromic-dichroic dyes. An InternationalLight Research Radiometer (Model IL-1700) with a detector system (ModelSED033 detector, B Filter, and diffuser) was used to verify exposureprior to the tests. Light from the monitoring source that was polarizedto the 0° polarization plane was then passed through the coated sampleand focused on a 1″ integrating sphere, which was connected to an OceanOptics 2000 spectrophotometer using a single function fiber optic cable.The spectral information, after passing through the sample, wascollected using Ocean Optics OOIBase32 and OOIColor software, and PPGpropriety software. While the photochromic-dichroic dyes were activated,the position of the Moxtek polarizer was rotated back and forth topolarize the light from the monitoring light source to the 90°polarization plane and back. Data was collected for approximately 15minutes at 5-second intervals during activation and every 3 secondsduring fade. For each test, rotation of the polarizers was adjusted tocollect data in the following sequence of polarization planes: 0°, 90°,90°, 0°, etc.

Absorption spectra were obtained and analyzed for each cell assemblyusing the Igor Pro software (available from WaveMetrics). The change inthe absorbance in each polarization direction for each cell assembly wascalculated by subtracting out the 0 time (i.e., unactivated) absorptionmeasurement for the cell assembly at each wavelength tested. Photopicresponse measurements were collected since multiple photochromiccompounds were used in the stretched films. Average absorbance valueswere obtained in the photopic region of the activation profile where thephotochromic response was saturated or nearly saturated (i.e., theregions where the measured absorbance did not increase or did notincrease significantly over time) for each cell assembly by averagingabsorbance at each time interval in this region. The average absorbancevalues in a predetermined range of wavelengths correspondingλ_(max-vis)+/−5 nm were extracted for the 0° and 90° polarizations, andthe absorption ratio for each wavelength in this range was calculated bydividing the larger average absorbance by the small average absorbance.For each wavelength extracted, 5 to 100 data points were averaged. Theaverage absorption ratio for the photochromic-dichroic dyes was thencalculated by averaging these individual absorption ratios. The averageabsorption ratio for the sample was then calculated by averaging theseindividual absorption ratios.

The results are reported below wherein the First Fade Half Life (“T1/2”)value is the time interval in seconds for the ΔOD of the activated formof the photochromic-dichroic dyes in the sample to reach one half themaximum ΔOD at 73.4° F. (23° C.), after removal of the activating lightsource. The Second Fade Half Life (“2ndT1/2”) value is the time intervalin seconds for the ΔOD of the activated form of thephotochromic-dichroic dyes in the sample to reach one quarter themaximum ΔOD at 73.4° F. (23° C.), after removal of the activating lightsource.

For each sample, the above-described procedure was run at least twice.The results reported below are for the stretched film alone as Example1A and the stretched film with the ¼ wave plate as Example 1B. Thetabled value for the Average Linear Absorption Ratio (Av. Lin. Abs.Ratio) represents an average of the results obtained from the runs. Theresults of the clear to linear polarized tests are presented in Table Ibelow.

TABLE 1 Clear to Linear Polarization Av. Lin. Example # ΔOD 0^(°) ΔOD90^(°) Abs. Ratio Av. OD T½ 2ndT½ 1A 0.34 1.26 3.70 0.57 50 138 1B 0.401.39 3.52 0.64 56 168

The clear to circular polarization studies were conducted in the samemanner as the clear to linear studies except for the modificationsdescribed below. The Moxtek polarizer was moved on the PI rotation stageto the side opposite of the film assembly. In order to do circularpolarization measurements, the circular polarizers need to face eachother such that the quarter wave plates are facing each other. To alignthe system, a known MG polarizer was placed in position prior to thecell assembly, oriented at 0 degrees for maximum transmission of thelaser light (Coherent Ultra-low noise laser diode module −635 nm). TheMoxtek polarizer was then rotated on the stage to achieve a nullposition. A quarter wave plate (from Melles Griot) was added to theoptical path just before the Moxtek polarizer. The Quarter wave plate(mounted on a goniometer from Opto-Sigma which had a rotation centerpoint 76 mm away from the top plate: this assembly was mounted on a 1.5inch damped rod from Melles Griot) was rotated to achieve a null signalof the laser. This ensured that either the fast or slow axes of thequarter wave plate was aligned with the Moxtek polarizers transmissiondirection.

Next, the Moxtek polarizer was rotated 45 degrees and the MG polarizerwas removed. The Moxtek polarizer now bisected the fast and slow axes ofthe MG quarter wave plate and produced either left hand or right handcircularly polarized light. Electrical dark, reference and darkreference spectra were collected for both left hand and right handcircularly polarized light by rotating the Moxtek Polarizer +/−90degrees (alternatively bisecting the fast and slow axes of the MGquarter wave plate from fast to slow and then slow to fast).

With the reference spectra collected, the sample was inserted into thetemperature controlled air cell. The Moxtek polarizer was rotated 45degrees to be horizontal and the MG polarizer (at 0 degrees) was placedin the beam path to produce a crossed polarizer configuration. The cellassembly was placed in the beam path and the laser was directed throughthe crossed polarizers and sample. The sample was rotated in 3 degreesteps through 120 degrees to find a minimum in the counts. Then thesample was rotated +/−5 degrees around this minimum at 0.1 degree stepsto locate the alignment direction of the sample to +/−0.1 degrees. Thesample was now aligned to be either vertical or horizontal. The laserwas switched closed, the laser directing mirrors and MG polarizer wereremoved from the optical path, and the Moxtek polarizer was rotated 45degrees to bisect the MG quarter wave plate again.

The data acquisition was done as before (120 second delay, 15 minutesactivation at 5 second interval data collection, 30 minutes fade or to2^(nd) half-life at 3 second intervals. The Moxtek polarizer was rotated+/−90 degrees throughout the data collection. Since the transmissionaxis of the Moxtek polarizer bisected the quarter wave plate (MG), thenthe rotation of the Moxtek polarizer went from bisecting the fast-slowaxes to bisecting the slow-fast axes, which created right hand circularpolarized light in one orientation and left-hand circular polarizedlight in the other orientation.

Measuring the stretched film with the quarter wave plate was essentiallythe same process except that the laser light intensity was reduced byusing a 1.0 and 0.5 ND filter. The results of the clear to circularpolarization studies for the stretched film alone are included asExample 1C and the stretched film with the ¼ wave plate are included asExample 1D and are listed below in Table 2.

TABLE 2 Clear to Circular Polarization Av. Cir. Example # ΔOD 0^(°) ΔOD90^(°) Abs. Ratio Av. OD T½ 2ndT½ 1C 0.58 0.58 1.00 0.58 66 214 1D 0.441.05 2.38 0.63 66 214

In Table 2, the clear to circular polarized sample 1D showed an averagecircular absorbance (Av. Cir. Abs.) ratio of 2.38 while the linear clearto polarized sample 1C showed an average circular absorbance ratio of1.0. Linear polarizers do not “cross” with circular polarizers provingthat ID was exhibiting clear to circular polarization.

It is to be understood that the present description illustrates aspectsof the invention relevant to a clear understanding of the invention.Certain aspects of the invention that would be apparent to those ofordinary skill in the art and that, therefore, would not facilitate abetter understanding of the invention have not been presented in orderto simplify the present description. Although the present invention hasbeen described in connection with certain embodiments, the presentinvention is not limited to the particular embodiments disclosed, but isintended to cover modifications that are within the spirit and scope ofthe invention, as defined by the appended claims.

1. An optical element comprising: (a) a photochromic linear polarizingelement comprising: (i) a substrate; and (ii) at least one coatingconnected to the substrate, the coating having a first absorption stateand a second absorption state and being operable for switching from thefirst absorption state to the second absorption state in response toactinic radiation, to revert back to the first absorption state inresponse to actinic radiation and/or thermal energy, and to linearlypolarize transmitted radiation in the first absorption state and/or thesecond absorption state; wherein the coating (ii) comprises an at leastpartially aligned, reversible photochromic-dichroic material having anaverage absorption ratio of at least 1.5 in an activated state; and (b)at least one birefringent layer comprising a polymeric coating orpolymeric sheet connected to the photochromic linear polarizing element(a), the birefringent layer being operable to circularly or ellipticallypolarize transmitted radiation.
 2. The optical element of claim 1wherein said photochromic-dichroic material comprises: (a) at least onephotochromic group PC chosen from a pyran, an oxazine, and a fulgide;and (b) at least one lengthening agent L attached to the at least onephotochromic group and represented by:—[S₁]_(c)-[Q₁-[S₂]_(d)]_(d′)-[Q₂-[S₃]_(e)]_(e′)-[Q₃-[S₄]_(f)]_(f′)—S₅—Pwherein: (i) each Q₁, Q₂, and Q₃ is independently chosen for eachoccurrence from: a divalent group chosen from: an unsubstituted or asubstituted aromatic group, an unsubstituted or a substituted alicyclicgroup, an unsubstituted or a substituted heterocyclic group, andmixtures thereof, wherein substituents are chosen from: a grouprepresented by P, liquid crystal mesogens, halogen, poly(C₁-C₁₈ alkoxy),C₁-C₁₈ alkoxycarbonyl, C₁-C₁₈ alkylcarbonyl, C₁-C₁₈alkoxycarbonyloxy,aryloxycarbonyloxy, perfluoro(C₁-C₁₈)alkoxy,perfluoro(C₁-C₁₈)alkoxycarbonyl, perfluoro(C₁-C₁₈)alkylcarbonyl,perfluoro(C₁-C₁₈)alkylamino, di-(perfluoro(C₁-C₁₈)alkyl)amino,perfluoro(C₁-C₁₈)alkylthio, C₁-C₁₈ alkylthio, C₁-C₁₈acetyl,C₃-C₁₀cycloalkyl, C₃-C₁₀ cycloalkoxy, a straight-chain or branchedC₁-C₁₈alkyl group that is mono-substituted with cyano, halo, or C₁-C₁₈alkoxy, or poly-substituted with halo, and a group comprising one of thefollowing formulae: -M(T)_((t-1)) and -M(OT)_((t-1)), wherein M ischosen from aluminum, antimony, tantalum, titanium, zirconium andsilicon, T is chosen from organofunctional radicals, organofunctionalhydrocarbon radicals, aliphatic hydrocarbon radicals and aromatichydrocarbon radicals, and t is the valence of M; (ii) c, d, e, and f areeach independently chosen from an integer ranging from 1 to 20,inclusive; and each S₁, S₂, S₃, S₄, and S₅ is independently chosen foreach occurrence from a spacer unit chosen from: (A) —(CH₂)_(g)—,—(CF₂)_(h)—, —Si(CH₂)_(g)—, —(Si[(CH₃)₂]O)_(h)—, wherein g isindependently chosen for each occurrence from 1 to 20; h is a wholenumber from 1 to 16 inclusive; (B) —N(Z)-, —C(Z)=C(Z)-, —C(Z)═N—,—C(Z′)-C(Z′)- or a single bond, wherein Z is independently chosen foreach occurrence from hydrogen, C₁-C₁₈ alkyl, C₃-C₁₀ cycloalkyl and aryl,and Z′ is independently chosen for each occurrence from C₁-C₁₈ alkyl,C₃-C₁₀cycloalkyl and aryl; and (C) —O—, —C(O)—, —C≡C—, —N═N—, —S—,—S(O)—, —S(O)(O)—, —(O)S(O)O—, —O(O)S(O)O— or straight-chain or branchedC₁-C₂₄ alkylene residue, said C₁-C₂₄ alkylene residue beingunsubstituted, mono-substituted by cyano or halo, or poly-substituted byhalo; provided that when two spacer units comprising heteroatoms arelinked together the spacer units are linked so that heteroatoms are notdirectly linked to each other and when S₁ and S₅ are linked to PC and P,respectively, they are linked so that two heteroatoms are not directlylinked to each other; (iii) P is chosen from: hydroxy, amino, C₂-C₁₈alkenyl, C₂-C₁₈ alkynyl, azido, silyl, siloxy, silylhydride,(tetrahydro-2H-pyran-2-yl)oxy, thio, isocyanato, thioisocyanato,acryloyloxy, methacryloyloxy, 2-(acryloyloxy)ethylcarbamyl,2-(methacryloyloxy)ethylcarbamyl, aziridinyl, allyloxycarbonyloxy,epoxy, carboxylic acid, carboxylic ester, acryloylamino,methacryloylamino, aminocarbonyl, C₁-C₁₈ alkyl aminocarbonyl,aminocarbonyl (C₁-C₁₈)alkyl, C₁-C₁₈ alkyloxycarbonyloxy, halocarbonyl,hydrogen, aryl, hydroxy(C₁-C₁₈)alkyl, C₁-C₁₈alkyl, C₁-C₁₈alkoxy,amino(C₁-C₁₈)alkyl, C₁-C₁₈ alkylamino, di-(C₁-C₁₈)alkylamino, C₁-C₁₈alkyl(C₁-C₁₈)alkoxy, C₁-C₁₈ alkoxy(C₁-C₁₈)alkoxy, nitro,poly(C₁-C₁₈)alkyl ether, (C₁-C₁₈)alkyl(C₁-C₁₈)alkoxy(C₁-C₁₈)alkyl,polyethyleneoxy, polypropyleneoxy, ethylenyl, acryloyl,acryloyloxy(C₁-C₁₈)alkyl, methacryloyl, methacryloyloxy(C₁-C₁₈)alkyl,2-chloroacryloyl, 2-phenylacryloyl, acryloyloxyphenyl,2-chloroacryloylamino, 2-phenylacryloylaminocarbonyl, oxetanyl,glycidyl, cyano, isocyanato(C₁-C₁₈)alkyl, itaconic acid ester, vinylether, vinyl ester, a styrene derivative, main-chain and side-chainliquid crystal polymers, siloxane derivatives, ethyleneiminederivatives, maleic acid derivatives, fumaric acid derivatives,unsubstituted cinnamic acid derivatives, cinnamic acid derivatives thatare substituted with at least one of methyl, methoxy, cyano and halogen,or substituted or unsubstituted chiral or non-chiral monovalent ordivalent groups chosen from steroid radicals, terpenoid radicals,alkaloid radicals and mixtures thereof, wherein the substituents areindependently chosen from C₁-C₁₈ alkyl, C₁-C₁₈ alkoxy, amino, C₃-C₁₀cycloalkyl, C₁-C₁₈ alkyl(C₁-C₁₈)alkoxy, fluoro(C₁-C₁₈)alkyl, cyano,cyano(C₁-C₁₈)alkyl, cyano(C₁-C₁₈)alkoxy or mixtures thereof, or P is astructure having from 2 to 4 reactive groups or P is an unsubstituted orsubstituted ring opening metathesis polymerization precursor; (iv) d′,e′ and f′ are each independently chosen from 0, 1, 2, 3, and 4, providedthat a sum of d′+e′+f′ is at least
 1. 3. The optical element of claim 1,further comprising at least one orientation facility having at least afirst general direction connected to at least a portion of thesubstrate.
 4. The optical element of claim 1 wherein the coating (ii)comprises two or more at least partially aligned reversiblephotochromic-dichroic materials, wherein the photochromic-dichroicmaterials have complementary absorption spectra and/or complementarylinear polarization states.
 5. The optical element of claim 1 whereinsaid coating (ii) comprises at least one self-assembling material. 6.The optical element of claim 5 wherein said self-assembling material ischosen from liquid crystal materials, block copolymers and mixturesthereof.
 7. The optical element of claim 1 wherein the coating (ii)further comprises a phase-separated polymer comprising an at leastpartially ordered matrix phase and an at least partially ordered guestphase, wherein the guest phase comprises a reversiblephotochromic-dichroic compound that is at least partially aligned withthe guest phase.
 8. The optical element of claim 1 wherein the coating(ii) further comprises an interpenetrating polymer network comprising anat least partially ordered anisotropic material and a polymericmaterial, wherein the anisotropic material comprises a reversiblephotochromic-dichroic compound that is at least partially aligned withthe anisotropic material.
 9. The optical element of claim 1 wherein saidcoating (ii) comprises a coating having a first ordered region having afirst general direction, and at least one second ordered region adjacentthe first ordered region having a second general direction that is thesame or different from the first general direction so as to form adesired pattern in the coating.
 10. The optical element of claim 1wherein said coating (ii) is adapted to transition from a first state toa second state in response to actinic radiation, and to linearlypolarize transmitted radiation in at least the second state.
 11. Theoptical element of claim 1 wherein the coating (ii) further comprises atleast one additive chosen from dyes, alignment promoters, kineticenhancing additives, photoinitiators, thermal initiators, polymerizationinhibitors, solvents, light stabilizers, heat stabilizers, mold releaseagents, rheology control agents, leveling agents, free radicalscavengers, gelators and adhesion promoters.
 12. The optical element ofclaim 1 further comprising at least one additional at least partialcoating chosen from photochromic coatings, anti-reflective coatings,linearly polarizing coatings, transitional coatings, primer coatings,adhesive coatings, mirrored coatings and protective coatings.
 13. Theoptical element of claim 1 wherein said birefringent layer (b) comprisesa layer having a first ordered region having a first general direction,and at least one second ordered region adjacent the first ordered regionhaving a second general direction that is the same or different from thefirst general direction so as to form a desired pattern in the layer.14. The optical element of claim 1 wherein said birefringent layer (b)comprises a polymeric coating chosen from self-assembling materials andfilm-forming materials.
 15. The optical element of claim 1 wherein saidbirefringent layer (b) comprises a polymeric sheet comprisingself-assembling materials, polycarbonate, polyamide, polyimide,poly(meth)acrylate, polycyclic alkene, polyurethane, poly(urea)urethane,polythiourethane, polythio(urea)urethane, polyol(allyl carbonate),cellulose acetate, cellulose diacetate, cellulose triacetate, celluloseacetate propionate, cellulose acetate butyrate, polyalkene,polyalkylene-vinyl acetate, poly(vinylacetate), poly(vinyl alcohol),poly(vinyl chloride), poly(vinylformal), poly(vinylacetal),poly(vinylidene chloride), poly(ethylene terephthalate), polyester,polysulfone, polyolefin, copolymers thereof, and/or mixtures thereof.16. The optical element of claim 1 wherein the birefringent layer (b)comprises a quarter-wave plate.
 17. The optical element of claim 1,wherein the optical element comprises ophthalmic elements, displayelements, windows, mirrors, packaging materials, and/or active andpassive liquid crystal cell elements and devices.
 18. The opticalelement of claim 17, wherein the ophthalmic element comprises correctivelenses, non-corrective lenses, contact lenses, intra-ocular lenses,magnifying lenses, protective lenses, or visors.
 19. The optical elementof claim 17, wherein the display element comprises screens, monitors,and security elements.
 20. The optical element of claim 1 wherein saidsubstrate is formed from organic materials, inorganic materials, orcombinations thereof.
 21. The optical element of claim 20 wherein saidsubstrate is at least translucent.
 22. The optical element of claim 21wherein said optical element is connected to a display element.
 23. Acomposite optical element comprising: (a) at least one photochromiclinear polarizing element comprising: (i) an at least partially orderedpolymeric sheet; and (ii) a reversible photochromic-dichroic materialthat is at least partially aligned with the polymeric sheet and has anaverage absorption ratio of at least 1.5 in the activated state; and (b)at least one birefringent layer comprising a polymeric coating orpolymeric sheet connected to the photochromic linear polarizing element(a), wherein the composite optical element is operable to circularly orelliptically polarize transmitted radiation.
 24. The composite opticalelement of claim 23 wherein said photochromic-dichroic material ischosen from: (1)3-phenyl-3-(4-(4-(3-piperidin-4-yl-propyl)piperidino)phenyl)-13,13-dimethyl-indeno[2′,3′:3,4]-naphtho[1,2-b]pyran;(2)3-phenyl-3-(4-(4-(3-(1-(2-hydroxyethyl)piperidin-4-yl)propyl)piperidino)phenyl)-13,13-dimethyl-indeno[2′,3′:3,4]naphtho[1,2-b]pyran;(3)3-phenyl-3-(4-(4-(4-butyl-phenylcarbamoyl)-piperidin-1-yl)phenyl)-13,13-dimethyl-6-methoxy-7-(4-phenyl-piperazin-1-yl)indeno[2′,3′:3,4]naphtho[1,2-b]pyran;(4)3-phenyl-3-(4-([1,4′]bipiperidinyl-1′-yl)phenyl)-13,13-dimethyl-6-methoxy-7-([1,4′]bipiperidinyl-1′-yl)indeno[2′,3′:3,4]naphtho[1,2-b]pyran;(5)3-phenyl-3-(4-(4-phenyl-piperazin-1-yl)phenyl)-13,13-dimethyl-6-methoxy-7-(4-(4-hexylbenzoyloxy)-piperidin-1-yl)indeno[2′,3′:3,4]naphtho[1,2-b]pyran;(6)3-phenyl-3-(4-(4-phenyl-piperazin-1-yl)phenyl)-13,13-dimethyl-6-methoxy-7-(4-(4′-octyloxy-biphenyl-4-carbonyloxy)-piperidin-1-yl)indeno[2′,3′:3,4]naphtho[1,2-b]pyran;25. The optical element of claim 23 wherein the polymeric sheetcomprises self-assembling materials, polycarbonate, polyamide,polyimide, poly(meth)acrylate, polycyclic alkene, polyurethane,poly(urea)urethane, polythiourethane, polythio(urea)urethane,polyol(allyl carbonate), cellulose acetate, cellulose diacetate,cellulose triacetate, cellulose acetate propionate, cellulose acetatebutyrate, polyalkene, polyalkylene-vinyl acetate, poly(vinylacetate),poly(vinyl alcohol), poly(vinyl chloride), poly(vinylformal),poly(vinylacetal), poly(vinylidene chloride), poly(ethyleneterephthalate), polyester, polysulfone, polyolefin, copolymers thereof,and/or mixtures thereof.
 26. The composite optical element of claim 23wherein the polymeric sheet (i) is chosen from a stretched polymersheet, an at least partially ordered liquid crystal polymer sheet, and aphoto-oriented polymer sheet.
 27. The composite optical element of claim23 wherein said polymeric sheet (i) comprises a sheet having a firstordered region having a first general direction, and at least one secondordered region adjacent the first ordered region having a second generaldirection that is the same or different from the first general directionso as to form a desired pattern in the sheet.
 28. The composite opticalelement of claim 23 wherein said photochromic linear polarizing elementis adapted to transition from a first state to a second state inresponse to actinic radiation, and to linearly polarize transmittedradiation in at least the second state.
 29. The composite opticalelement of claim 23, wherein the birefringent layer (b) comprises aquarter-wave plate.
 30. The composite optical element of claim 23wherein said birefringent layer (b) comprises a polymeric coating chosenfrom self-assembling materials and film-forming materials.
 31. Thecomposite optical element of claim 23 wherein said birefringent layer(b) comprises a polymeric sheet comprising self-assembling materials,polycarbonate, polyamide, polyimide, poly(meth)acrylate, polycyclicalkene, polyurethane, poly(urea)urethane, polythiourethane,polythio(urea)urethane, polyol(allyl carbonate), cellulose acetate,cellulose diacetate, cellulose triacetate, cellulose acetate propionate,cellulose acetate butyrate, alkylene-vinyl acetate, poly(vinylacetate),poly(vinyl alcohol), poly(vinyl chloride), poly(vinylidene chloride),poly(ethylene terephthalate), polyester, polysulfone, polyolefin,copolymers thereof, and/or mixtures thereof. (b) comprises a polymericcomposition.
 32. The composite optical element of claim 23 wherein saidbirefringent layer (b) comprises a layer having a first ordered regionhaving a first general direction, and at least one second ordered regionadjacent the first ordered region having a second general direction thatis the same or different from the first general direction so as to forma desired pattern in the layer.
 33. The composite optical element ofclaim 23 further comprises a substrate formed from organic materials,inorganic materials, or combinations thereof.
 34. The composite opticalelement of claim 33 wherein said substrate is at least translucent. 35.The composite optical element of claim 33 wherein said substratecomprises untinted substrates, tinted substrates, photochromicsubstrates, tinted photochromic substrates, and linearly polarizingsubstrates.
 36. The composite optical element of claim 23, wherein saidoptical element comprises ophthalmic elements, display elements,windows, mirrors, packaging materials and/or active and passive liquidcrystal cell elements and devices.
 37. The composite optical element ofclaim 36, wherein the ophthalmic element comprises corrective lenses,non-corrective lenses, contact lenses, intra-ocular lenses, magnifyinglenses, protective lenses, or visors.
 38. The composite optical elementof claim 36, wherein the display element comprises screens, monitors,and security elements.
 39. The composite optical element of claim 23connected to a display element.
 40. The composite optical element ofclaim 39 further comprising at least one additional at least partialcoating chosen from photochromic coatings, anti-reflective coatings,linearly polarizing coatings, transitional coatings, primer coatings,adhesive coatings, mirrored coatings and protective coatings.
 41. Anoptical element comprising a circular polarizer connected to a substratecomprising packaging material for light-sensitive products wherein saidcircular polarizer comprises an assembly of a a quarter wave retarderand a linearly polarizing coating or an at least partially orderedpolymeric sheet comprising an at least partially aligned reversiblephotochromic-dichroic material having an average absorption ratio of atleast 1.5 in an activated state.